We used mammoth, and math-u-see..then we tried RS..
My child is delayed in many areas, but this math has been great for us! She loves her abacus.. seeing and touching is something that really makea a difference for her.. she is a visual learner.
you can get the material for discounts from other parents too. There are someon this site selling curr. and on the yahoo site as well. I found my 1st set on ebay. I myself have level B. and soon Level C
as well as alot of the manipulatives for $57.00 plus shipping. You don't have to buy ALL the mani. I made due w/ things that were cheaper.. say the dollar store. I love this curr!! She just gets it!!!