My personal experience with all cycling gear is that I pretty much HAVE to try it on. I cant order it of the internet because, unlike some other types of clothes, there are several reasons why I want my cycling gear to fit just right and sizes are all over the place (one brand's M is another's XL). Having the correct size makes shorts/bibs much more comfortable. You want it tight so the chamois stays where it needs to be, and because the material has a lot of give to it.

So fit is important, but some more expensive gear is really superior to some of the cheaper stuff. That does not mean you cant get decent stuff on the cheap, it just takes a little more effort. Also, there is a certain point where gear becomes more and more expensive wile only being marginally better. My LBS has 20 euro bibs but they are extremely crappy. You can get a pear of Pearl izumi bibs on sale for 50 and they will last longer and are more comfortable. It is a difference of night and day. However, there are also 200 euro Assos bibs. Sure they may be nicer, but the difference becomes smaller as you go up in price. Go for a happy medium.