I don't recommend it for the simple reason that all of those are easy to get invited to for free and/or have better alternatives. But I guess it's an option if you're desperate. At least the money will go towards site funds instead of the pockets of some shady invite seller stealing their business.

Note the practice is disreputed in the community under the following reasoning: most private trackers are kept safe by a combination of at least nominal exclusiveness, small size compared to the usual targets, and good opsec from staff and site owners. Selling invites to absolutely anyone who can muster up enough money kills the first reason, dilutes the second and tests the third (handling donations securely for all parties involved isn't easy). IPT is doing great so far, though