I'm not even sure I should share this with you--if word gets out about this, I'll lose my chances at bargain supplies too! Well...since I've already got more supplies than I could possibly use up in the next few years, I suppose it won't hurt to let you in on my secret.
If you are getting started with watercolor, you may hear or read on the internet that every artist likes different brands. Of paint, paper, brushes--you name it. So if you're like me, and you have hardcore FOMO on the "perfect" supply for you, you'll be very tempted to start spending outrageous amounts of money on supplies. Luckily, I built my collection of watercolor paint in a fairly cost effective manner: with paint lots from eBay.
You can save 50% or more over list price by bidding on new or gently used lots of watercolor paint. Keep in mind that watercolor paint pretty much never goes bad--just add water and it will come back to life. Now, you'll want to watch out for the price per mL: $2.50 is the most I would pay per 5mL tube of brand name paint. A slightly higher per tube amount for 15mL is reasonable, say up to $6. But once you decide on an amount you'd consider a good deal for paint, you can build a collection quickly. I wanted to keep my options open and accidentally ended up winning multiple bids when using this scheme, so maybe also learn from my mistakes, ok? My husband was not thrilled when nearly 100 tubes of paint showed up on our doorstep while we were on vacation.