Well like I said; Contact those members on MCB and they'll get you settled with some seals and a tool, You're probably looking at around $35 bucks to get it in working condition after you do it'll be good for ages. (If titus is nice he'll loan you a tool if you promise to send it back)
There are 2 types of grips for the standard Sheridan frame. Normal Sheridan 45 grips and PPS battle grips. Battle grips add finger groves and are pretty comfortable but I prefer the original grips, Even though I have large hands I like to have a small frame. Battle grips got for around $50, you can find a pair of normal grips on Baccipaintball for about $15. If you need help finding a pair let me know.
There are also Wood grips that range in price from $20-$45 depending on make/manufacture.