I'm real new to this and I've read previous threads about what to get for a used or new fixed/ss bike but didn't find what I was looking for. I'm willing to spend about $350 for a used bike either fixed or ss and just want something that rides well and looks good riding casually and running my dog

I just don't want to end up getting a kooky 'begginers' bike that's easily outgrown but rather something that I can use for a long time. If anybody here surfs, it's like starting off with a funboard and learning to surf on it and never using that board again because it has neither the function of a longboard or shortboard. I want to avoid that scenario with a bike I get.

Can anybody direct me towards used dealers or places/sites I should look at, types of bikes, etc. Any direction to narrow it down would help. I'm in orange county and often in Los Angeles if that helps.