If you need a fair bit of speed, then go with Chai. Otherwise, an ACME screw should deliver what you need given that size. You should also check eBay more generally, though. You can often find full screw assemblies (ballscrew, nut, mounting blocks) in that size range for between $100 and $200 in C5 accuracy. Delivery costs to Argentina are something that has to be factored in, as well.