Any of the “name brand” machines currently made in the US will do a good job for you. You will want a coarse lap for removing larger amounts of material, and a 600 grit lap for fine cutting. A cheap topper will work for coarse shaping, for a while. The 600 should be a good quality lap like these: http://www.arrowheadlapidarysupply.com/catalog/item.php?unid=4140&prodpa=0
After fine cutting, you’ll need prepolish and polish laps. I would suggest one of the Gearloose starter kits: http://gearloose.co/shop/highest-performance-starter-kit/
While you’re on the Gearloose site, take a look at the Product Charts. Some good information there.