Lots of people in Texas sell games. It all depends on what game you want and what you want to pay for it. I work for a shop in Austin, but we sell high retail - even on something like a Defender upright which we're picking up next week - so most hobby people don't buy from us (and I don't blame them).
A lot of us sell individually. We just need to know what you're looking for. I don't sell my games anywhere near what my work does (even though the work done to them is comparable or better), but I also don't have a huge selection of games I want to get rid of that are highly desirable, either.
As for places to play in Austin (or nearby), the only places that technically have "arcades" are the Dave & Buster's, Main Event, and Austin Park & Pizza (that I know of). Other places like movie theaters and bowling alleys have small arcades in them. And there are a few bars that have a decent selection - Kung Fu Saloon and Warehouse Pool & Billiards are a couple.
And that doesn't count the assorted bars, pool halls, and laundromats that have a couple games in them...