Thanks a bunch @PuffinMuffin , I still have my heart set on buying an old bike and converting but information like that helps out a ton for someone as green as me.
I think I'm leaning towards doing something with an old mountain bike... I've seen a few before and after results and I am hooked on that idea.
try to get a frame that has semi horizontal dropouts so you don't need a chain tensioner. also helps with the looks.
i think specialized stumpjumpers have those, some gt frames as well. those would be good to convert to a fixie. you could build it into a tracklocross bike basically. you could just buy an old 90s mtb that has those dropouts and a suitable and well working crank, take the cassette and freewheel off, put a fixed cog on, and leave the middle or outer chainring only. disconnect and strip all gearing parts and possibly brakes and you're done.
i might attempt this when i have enough parts in my used parts bin and find a suitable frame.
EDIT:
forgot to add that the fixed cog and chainring probably demand different chains, but if a bike had a 7 speed cassette, the chain for that might still work on the fixed cog. or you buy a track cog, chainring and chain altogether to be sure. but that would be all you need to buy i guess.