Sepia, I've recently gone down this road as well. About a year ago, I got a YashicaMat-124 and it was a revelation. A TLR will open your eyes to whole new ways of making photographs. More recently, I have acquired a Mamiya 645 Pro 1000S. This is a 70s vintage pretty rugged mechanical MF SLR, although there are more electronic doo-dads available if you like. I'd rather a 6x6 as well, but that seems to get into more expensive territory. Careful shopping should be able to find you one for well under $300. If you are patient, you may find one in what I guess is a wedding photographers kit, with aluminum case and usually one or more additional lenses and accessories. These WILL be well used, but normally not abused, and with a new set of seals or a full CLA should provide many years of service. Accessories and parts and pieces are available for reasonable cost, even new. My enlarger is essentially the same as yours (C700) and everything has worked out quite well. You will want a 70 or 80mm lens for your enlarger. Negative holders can get expensive but can be fabricated out of cardboard if necessary until you find a metal one at a reasonable price.