Always always ALWAYS do your research before even considering buying any animal. And while plenty pet store employees are misinformed, MANY ARE NOT. Weeding out the bad from the good can be difficult sometimes, which is why it is entirely up to you to read up on any potential animal. You shouldn't rely on someone else to do your homework.
I work at PetSmart, and find it entirely insulting when people say not to listen to pet store employees. Yes, this person was completely wrong, but you should have researched everything first, and then you could have taught them something.
If someone asks me to start from square one about fishkeeping, I brief them about cycling, stocking, why goldfish aren't great first pets, and how bettas are the most abused fish in the fish trade, and then write down many useful URLs (such and tropicalfishkeeping.com) to tell them to research before even buying a tank. Many of them thank me for my references and leave happy and satisfied, and I'm happy because I feel like I've given someone a great start into a great (and addictive) hobby.
Try to do some extra chores and pick up a few extra dollars. With that, you can find a cheap 5 gallon set-up and divide it. WalMart has the Hawkeye system for $25, plus you'd need a heater (about $10) and gravel/decor (around $20). With that set-up, you're less likely to spill water onto the floor because you aren't trudging back and forth with a slippery bowl every time you do 100% water changes. You will only have to do about 30% a week into a sturdy bucket with a handle, therefore it would be less likely to spill everywhere. Your bettas will also be much healthier and you can see their true personalities.