Everybody needs a 6x6. Personally, I'm a fan of TLRs, but there do seem to be people who don't like them---I think mostly because of the reversal in the WLF, or the inconvenience of long-lens arrangements. As plenty of other people have pointed out, you can try out a decent one in the Rolleicord or Autocord class fairly cheaply, but it isn't all *that* expensive---though over your current budget---to get into a Rolleiflex, which will stand up to any MF system on the planet for image quality.
It basically confines you to a normal lens, and you probably already know whether that would be acceptable or not. To my taste it's a feature.