guys, what's the best way to prepare for suitefoundations without paying for the NS training?

very good question, try reading up all the Netsuite Guides (available in help for download) concentrate on basic guide and Admin guides. Touch on order & inventory management, suitebuilder(old e-com), accounting, CRM analytic/searches etc. Skip SCA, Open Air, SuiteScript, suitetalk. Most important play with the sandbox or dev account if you have access to it.