1- If you are looking for site that has keyword X in their domain name, you can search them in Namedroppers.com. For instance
this links finds the sites with a domain name including keyword "vbulletin"
I wish Google had this feature (well actually it has partial support for this). When you search a too general concept I find it better to first locate the sites that uses this keyword in their domain name so this is where namedroppers.com is helping me.
2-
NameCheap registers or transfer domains for only 8.88 USD. Nice price and I thing customer support is working fine too. (Though I dont have a extensive experience with them, this is just an first impression)