Wouldn't personally recommend SM58's for recording vocals. Most people would go for a condenser mic (as opposed to a dynamic mic such as 58's, 57's etc) to record vocals or acoustic instruments. It depends on your budget really if you're looking to buy. I have an SE Electronics SE2200a on vocals and acoustic guitars and it sounds good enough which was only £139 and also a Neumann MK147 which cost a fair bit more and is gorgeous.