If you don't care what veneer you use, look for sales. There's always some leftover veneer going on sale somewhere - usually something that couldn't be sold or maybe is not consecutive. If there's a shop that does veneer work in your area, stop by and ask to buy any leftover veneer they have. They always buy more veneer than they need for a job because you can't risk being short. And sometimes they buy veneer that just doesn't sell.
eBay sells veneer for reasonable prices but the shipping charges make it expensive in small quantities.
But the best thing is to plan for both sides when you order your veneer. Where ever you buy your show veneer, ask them for some decent quality veneer for the non-show face
Once you do some amount of veneer work, you'll have a bunch of odds and ends that you'll wonder where to store - it seems to multiply like rabbits.
Go into the world and do well. But more importantly, go into the world and do good.