Here's the catch, you have to purchase at least $50 worth of supplies from this vendor to get the UPS price of $34 a bottle of Ultrafina. Buy 2 bottles and you're set!
3M Waxes, Compounds, & Polishes
It's cheapest I've found so far.
Also, I thought I found the Ultrafina pad but not quite sure if this is the cheapest out there.
3M™ Perfect-It™ Ultrafina™ BLUE Foam Polishing Pad, 05733, 8 in
If you need to buy both, Gofer Auto is probably the best bet.