I guess if you wanna make a Rock-Coverband it would be a good idea to make the best out of it - money! And thats how you should get some musicians. Ask a few dudes, tell them you can guarantee a certain number of gigs per year and voila - you´ll be surprised how many interrested folks you will find. You make it for the fun of it - the others for the money - now its up to you weather you have a problem with that or not.