You're right, generally if you are -250 you will have a tough time getting them to commit, unless your schools is rated highly in just about every category. But pay attention to how far their interest bar is as well, and if they are Top 8 or Top 10 with their teams yet.
5 star guys are tough to get if you aren't one of the powerhouse schools in NCAA 11, and it's very difficult to recruit against the powerhouse schools because they are an A+ in just about everything. I don't recommend pursuing them unless you are close to the top b/c the other schools recruiting them will spend a lot of time on them and have a lot to offer.
If you really want to get some 4 star talent on your team I would find the top 10 guys within your pipeline states that you are within range with or close to within range with. Also look for guys that are at Top 10 instead of Top 8. You'll want to invest 60 minutes in them every week. If someone commits to you or another school just add a new player.
By about week 8 or 9 you will be adding the 3 star guys that you would normally end up with so it's worth the risk and you can usually score a couple of a 4 star guys that way.
If your school isn't "ready" to recruit 4 star talent yet, I still recommend taking a gamble on maybe 1 or 2 4 star guys and then just pushing for the highest rated 3 star guys that you can get.