Have you tried searching online? (Sorry popped over from hair!) in hair we can get out own branded hair care and they even do nail varnishes from a company called Options (sorry they don't do tan!) it's all ready made products - fab quality! And you pick your bottles and they add your logo. Maybe it's something like this? I'm sure there is other companies like this xxx
I would guess that they could just be buying the larger 5L bottles and just re-bottling it into smaller ones that they can charge a bit more for as I would expect to have your own brand made up would require a reasonable quantity order to be worth the manufacturers while.
Its not too bad doing something like that with hair and beauty products but with tanning solution the DHA in the solution has a bit of a limited shelf life so you wouldnt want to buy loads with your own label on it and hope you can sell it before it goes out of date.
If its just instant tan rather than one that develops your skin with the DHA then shelf life wouldnt be a problem.
Even though they have their own branded bottles, does it look good, feel a quality product as branding is important.
There are a few wholesale companies out there that offer "white labelling". This is how many new tans come onto the market - same solution, different name.
However, if you want to formulate your own this becomes expensive as you would need a cosmetic chemist to formulate, testing etc etc etc.
You could approach one of the manufacturers in the UK and "tweak" one of their existing formulas
All cosmetic products have new procedures within the uk and have to be registered accordingly, wheather it is rebranding or manufacturing the correct authorities need to be notified this creates a safer environment across the board. When creating a new brand various procedures need to be adhered to which can be quite costly with safety data required, if only supplying small quantities this is not viable. Failure to comply with standards, and have relevant data could cause problems.