You're better off asking for bikini pictures at a lower price and then working your way up. Or even pictures of their stomach for like $15, then make the next request $30 for their ass in a thong or whatever. Girls respond much better to the emotional attachment and dopamine rush they get from doing little things rather than straight up asking for nudes, even if you're gonna give them a high $ amount upfront.
The hardest part can be getting them to trust you, that's why you start small and work your way up.
Source: my dumbass whose spent way too much money on cam sites. As someone whose asked multiple girls on cam sites to see them nude for $100 and they say no. but if you make the requests in small increments the same girl would eventually get nude over 5 payments of $20 for dumb random shit. Trust me they would rather see 10 payments of $1 show up in their account rather than you sending $10 all at once.
Why? Dunno. Lotsa girls don't think logically. IG is gonna be harder though especially if they've never sent nudes but the advice is the same.