I've heard that OMNI Manufacturing builds some affordable cultipackers with a simple design (which is always a plus!). Also too, they've started using ductile iron wheels (vs. regular grey iron wheels) because they have 300% more tensile strength. Here's a link to their cultipacker page on their website:

http://omni-mfg.com/Cultipackers-C110177.aspx?sid=10512