I've been where you are now Blue (probably when I was about your age) and to be honest I think you'd be making a big mistake. I really do.
Reverting from Matrix to Tigi would be a massive step backwards - why carry a brand that is 1. Old fashioned, 2. Purely cosmetic, 3. Available everywhere including the nastiest discount stores, and 4. Made by the same manufacturer (Unilever) as Tresemme - another "salon brand they bought" and watered down to nothing to sell to the consumer market?
You may as well go blow your money on a Rover car - they were good once too.
I would urge you to think about how you're feeling and ask yourself if you want the same for your clients? So, you're feeling like you spend a lot of money every month and your rep doesn't appreciate you? You feel as if you're not being given enough incentive or promotional offers ('what do you mean I have to buy 4 boxes of each product to get a free poster/shelf/sample? I just bought 6 boxes of each last month and 3 items aren't selling yet, and that's due to the fact I have no promotional materials to push them!', 'God, I am sat here with all this colour and all these products and now he wants me to buy yet another box of new stuff/training date (that's nowhere near me)/ refusing to have a tech come visit me' etc.)?
So it's a free world, and you could be spending your money with someone who appreciates it and values you more? After all, you spend ALOT of money right?
Hold onto that feeling and imagine you go with Tigi -
1. You still have all your Matrix products to sell
2. You still have all your Matrix colour to use.
3. You now have competing products from Tigi.
Your client who spends £35 every 6 weeks notices you are using different stuff. She recognises it from TK Maxx. You are charging about £8 for a shampoo. When next in TK Maxx she spots the backwash size priced at a fiver.
Instantly you have aligned your entire "worth" with TK Maxx. Your service, your brand, and your perceived level in the market. What's worse is that for her you are still charging the same prices as you did when you used that nice organic stuff in the white bottles. Suddenly you are not so special anymore. You use stuff she can buy herself in a discount store, and cheaper than you sell it for too! Suddenly, you might seem a bit 'expensive' for what you offer.
She might be feeling a bit down one day and decide to 'treat herself'. Let me give you a tip ... when a woman wants to treat herself she doesn't go looking at the usual Revlon make-up stand in Asda - it's a bottle of Chanel, a pair of Jimmy Choos, perhaps a Radley handbag.
Where does a (now overpriced) bottle of Dumb Blonde shampoo from you and your salon fit into that equation? Where does your salon even fit into that equation? Perhaps that nice salon down the road might be worth the extra £15 for her appointment? After all, she wants to treat herself, and they have nice organic products in white bottles too.
LOL
At the end of the day your rep is just a rep. For what it's worth, I have seen the "Matrix Flowchart" of what they are allowed to offer if an account is "under threat" i.e. like yourself, and L'Oreal are quite strict about what can be done. One of the things they consider is "3 or more stylists?" in which case they would offer a free technical visit to your salon. Right now, the best you would be able to get is probably a free training credit outside of the salon on a course with a value of about £99. This has to be approved by head office too as L'Oreal charge the distributor for each delegate who is on a course - the "Discover Matrix" course is the only one that is provided to the distributor for free. This is why it's hard for reps to be able to 'show their appreciation' at times - I'm sure your rep personally appreciates your spend and values you as a customer, but he has a boss (Alan Howard) who buys stuff from a supplier called Matrix, and he, as a mere rep, is pretty much left out of the equation when it comes to what he can offer and what he can't to Matrix users (probably much to his despair).
Sorry for the long reply, but I don't want you to make the same mistakes that I made when I was in my twenties and had my first salon due to the same frustrations I too was experiencing. The fact my eyes need to be help open with matchsticks right now probably doesn't help either and in the morning I'll read this all back and think, "Boy you can waffle when you're tired". LOL
But basically, you're on the right track. You have your first salon and your monthly spend suggests you're heading in the right direction. From here you need to move on up, not down, when it comes to products and services available. Part of your problem is probably expecting too much - you care so much for something, get right into it and then feel disheartened when there is no more left to learn. Slow down, otherwise you'll go through 10 different product lines by the time you've been in business an equal number of years.
Have a chat with your rep and explain you're feeling a bit bored with what's on offer. Ask him what he's got that's new, but explain you want something with more rewards or opportunities than he is currently able to offer with Matrix - something they have more leeway with. The very fact you cannot ever get Tigi VAT FREE should tell you that a partnership with Unilever would be even more restrictive and unsatisfying than Matrix. I'm sure he'll be happy to introduce a second line to you that would sit nicely alongside Matrix, after all, Alan Howard/EWD do stock quite a few lines, and there will be some that they can offer more movement on.
My last piece of advice would be not to get too hung up on price, and concentrate instead on the quality/exclusivity. In our salons we sell a hairspray that costs £18. We have a conditioner that sells for £23. We even sell a box of 20 teabags that costs a staggering £12.My best selling wax is £20. I don't stock them because they are expensive, I stock them because they work better than any other I have tried, plus they are exclusive to me and my salon in our local area - they are special "treats" that clients can and do buy for themselves to cheer themselves up in an otherwise gloomy world. As the L'Oreal saying goes, "Because I'm worth it" is worth remembering.
Hope some of this helps.
Good luck!