Here are some things you should know about Ibanez 7's on the used/new market:
The Ibanez RG7420/7421/7620/7621/1527/S7420 are all made in Japan.
The Ibanez 7321/New Ibanez S7 are made in korea/indonesia
The Ibanez 7420 and 7620 have trem's. The 7421 has the Lo TRS 2 (disliked by many players) and the 7620 has the Lo Pro Edge 7, widely preferred by most players over 7420. The 7420 has Ibanez stock pickups and the 7620 has dimarzio new 7's.
The Ibanez 7421 and 7621 are both
fixed bridge guitars. The 7421 has Ibanez stock pickups and the 7621 has Dimarzio new 7's.
Used value on a 7420 is anywhere from $300 to $400, sometimes a tad bit higher.
Used value on a 7421 is anywhere from $250-$350.
Used value on a 7621 is anywhere from $400-$500
Used value on a 7620 is anywhere from $500 up to as much as $800. This model was very pricey when it came out ($1300)
The 1527 is a prestige level axe which comes with a very nice case. I believe they run $899 new. You can get them on a no interest payment plan at AMS. I have never played one but I read that they are very nice.
The 7321 is the affordable entry model. If you want a brand new guitar for your $, the 7321 is a good bet. its fixed bridge, which lends itself to downtuning and makes it simple to set up and play.
If you want the best bang for your buck, the 7421 is probably it if you are interested in a used guitar. The guitars play very nice, and if you get a good deal, you can add 2
dimarzio pickups later on and still be under your $500 mark.
I have not played any other brands of 7's, but I have heard that the schecters necks are like baseball bats LOL =)
If you are an Ibanez fan, go Ibanez. You won't regret it. Hope this helps =)