If you are going to the show next week, use it as a way to research different products. Go with nothing on your own nails and get a sample applied of as many brands as you can - there are so many that you might have to make a list of your main preferences before you go. Make a note of which brand is on which finger and make notes on how easy it was to apply, how long it took etc. Keep them on for two weeks to see how each one wears and them remove them yourself one at a time to see how easy removal is for each product.
I know this sounds extreme, but this is the way I did it when all the products first came out a few years ago. I spent ages waiting at each stand, but it was well worth it and I was able to make a really informed decision before I bought into a range. I ended up with a table of pros and cons on eight brands based on my own experience.
It is worth finding out the cost of the relevant lamps and products, but the cost per bottle is only relevant when you first buy because the difference between an expensive brand and a cheaper brand is minimal (pennies) if you work it out per service.