Iomoio
No matter how weird its name sounds, let me tell you, this service is pretty impressive. Prompt support staff, over million tracks, great prices, what else would you need?
- Prices are $0.10 per track, but if you will make use of bonus this site provide ($25+$15 and $50+$35) it will certainly be much less.
- Over million tracks in the database. Great search engine with auto-fill function.
- Security is provided by 128bit SSL certificate.
Payment methods currently provided: 
Try out Iomoio as soon as you can!