What should I look for when buying a pasta roller?
There are a few consideratons that I can think of:


How durable the device is.  Generally, this is going to mean that you want something metal &amp; heavy, but I'd really look at reviews of any model that you plan to buy online, particularly from something like Amazon which lets you see those 1 star ratings, and you can see why people rated them so poorly.
How it clamps down to the work surface.  I don't care how heavy it is, if it's a hand-crank, it's going to walk all over the place unless it's well secured to your counter.  If you don't have a counter that's got a lip that you can clamp to, and you don't have a table that you're willing to possibly mar from the clamps, you might have to look for something else (or bolt/screw it down to a large board)
Size (width) of the feed.  There are some that are larger, which might be useful for making some pastries as well as pasta.  (and then there's dough sheeters, which are huge and expensive, but are 18" or wider, typically).
How many different thickneses the dial has, and what the min/max thickness is.  Again, a thicker one can be used for other pastry applications, but it also makes it easier to work the ball through that first time.  (I've only ever used one where the thickest size was a pain ... so it's not a common problem.  All I remember was it was a friend's, and it wasn't an Italian company)
Hand crank vs. motorized -- almost every hand crank roller can be converted (as the handle detaches for storage, so the motor just connects there), but the difference in cost is significant.  (~$50 vs. ~$150.  If you already have a Kitchen Aid stand mixer, they sell an roller kit, but it's in that $150 range.)  Even if you got a motorized roller, I'd look to make sure that the motor detaches and it had a hand crank ... as it lets you keep working should the motor go into thermal shutdown, but it also means typically means that the company sells the roller and motor individually should one part die down the road.  (you should try to verify that, though)
Accessories -- so, other than an add-on motor, the two main accessories you'll see are cutters (fettucini and something thinner are typical), and ravioli stuffers.  Personally, I'd say the raviolli stuffers aren't worth it.  If you want consistently sized ones, get one of those little forms that you run a rolling pin over to cut, as the cleaning of the attachment ones means it's not worth it unless you're making a huge batch.  (which you can do, then freeze 'em, but I never have).  I think the cutters are worth it (and are typically included in even the $40-60 models) if you're going to make fettucini.  For the thinner strand pastas, I actually prefer extrusion over rolling.  (although, I think capellini/angel hair may need to be rolled vs. extruded, but I'm not a fan of that size of pasta).  For wider noodles, it's generally not a big deal to hand-cut 'em. 


As for the question on price ... not really.  There are a few major price bands for the good motorized vs. non-motorized, and most stores keep 'em in those ranges.  The really cheap ones are going to break, or jam, as they just have a lower build quality.  If you see something much over $150, I'd question it.  Unless it had an exceptionally wide roller (and that was a feature you wanted), I can't think of a reason to shell out that much.

I'd try to stick with a model that I could find well reviewed  (with at least a dozen people having reviewed it if it's purchaser-submitted vs. something like Consumer Reports or America's Test Kitchen), and preferably, a model that's been on the market for years, as there's very little innovation -- a brand new model was likely made to trim costs, or because it's something the company never made before (and thus, untested).