Rough numbers, and every one of these varies by vendor and market, so confirm current pricing before you budget on it.
Per deal you control: earnest money, commonly $500 to $1,000 on a wholesale contract though sellers and their agents sometimes want more, and it's at risk if the deal dies. A JV agreement and a joint disbursement instruction to the closing agent, which cost paper once your template is drafted. Attorney review of that template, a one-time few hundred dollars in most places.
Monthly, if you're the acquisition side: a CRM in the $50 to $150 range, list pulling around $50 to $100, skip tracing usually priced per record from a few cents up to about 25 cents, e-signature $20 to $40, and a dialer if you're calling, which is where budgets balloon. If your JV partner is handling dispo, you're paying none of their side.
So the floor to participate as the acquisition partner is a deposit you can afford to lose plus a way to find sellers. Someone driving neighborhoods and knocking can start near zero on software and pay in hours instead.
One cost that doesn't show up on either list: the closing agent. Some will split an assignment fee two ways on the settlement statement without comment, some refuse, and practice differs by state and by company. Ask before you sign the JV, because the workaround is usually a double close, and that brings a second set of closing costs plus a funder's fee that comes out of the same spread you were splitting.