While the price of SVT-40s has basically doubled since they first became widely available, in retrospect $300 for a historically important and interesting full power military self loader was ridiculously cheap. I consider myself very lucky to have gotten in on a cheap one. It is worth noting that we still pay way less for an SVT-40 than Americans do.
As for the rifle itself, I quite enjoy shooting mine. While they are quite long, they are actually surprisingly light and svelte. The action does a decent job of taming the recoil. Accuracy in my particular rifle is ok, nothing spectacular. I've heard it repeated that the SVT-40 wasn't overly rugged, and can have parts break, I don't know if this is true. Reliability wise, I don't recall ever having a stoppage. Finally for ammo, if you want to avoid corrosive surplus, buying factory 7.62x54r is cheaper than most of common milsurp calibers.