The only rifles that are Dragunov's are:
Russian SVD 7.62x54R $8000+Ultra rare, just about 100 in country
Russian Tigr 7.62x54R $2000+The Tigr is basically a 20" barrel version of the SVD without the military features, a 'sporterized' hunting configuration
Russian CA Armory Tigr 7.62x54R $3500+Full on military look like an SVD, but 20" barrel still
Chinese NDM86 7.62x54R $3500+Almost exact copy of the SVD
Chinese NDM86 7.62x51 $2500+Everything else is basically an AK on steroids one way or the other, including the PSL/Romak. There's a lot of hype to take advantage of the Dragunov fame, but if you want a 'real' Dragunov, your choices are limited and you are going to definately pay a lot more than a PSL. PSL's are fine for what they are, just be careful on price. I wouldn't pay more than $800ish for one depending on accessories.
On a practical level there isn't much difference in accuracy or reliability between Dragunov's and the PSL, they both get about 2-4 MOA in the 54R versions.
The 308's will outshoot the 54R PSL and Dragunov all day long however, many people routinely get sub MOA and half MOA does not seem to be uncommon.
If your intention is to get some cheap 54R and go blasting for fun, then you probaby want a PSL...they are cheaper and are definately fun. Once you know anything about an AK you'll be right at home with a PSL because it's the same, just larger.
On the other hand if you want a tack driver, neither the Dragunov or the PSL is probably not the best choice unless you can find one in .308. They aren't really sniper rifles in the sense that we think of them, they are designated marksman rifles intended to extend the range of an infantry squad, not take headshots at 1000m.
If you are interested in the actual Dragunov for what it is, then a PSL is definately no substitute IMO. There is a huge difference in design and craftsmanship between the two, the internals are completely different and even the sensation of shooting is very different. To me there is no comparison, they are like apples and oranges even though they shoot the same caliber. All I can say is that a Dragunov is really a Dragunov and you feel it...everything else isn't
As mentioned, check out Dragunov.net for more info. Berg has great information up and with a little reading you can get a better idea of what the differences between them are.
Z