I've noticed a few sellers on ebay are a bit sneaky as in they offer a body fairly cheap and then sell the headmaster partner for $40+ . These days I wont even buy a targetmaster robot without their TM partners. When I first started collecting again about 13 years ago I made the mistake of buying Triggerhappy and Slugslinger without their TM partners and now would have to pay $35+ each if I wanted their partners last I checked.

So in short, these days unless part of a big junker lot never buy a G1 toy without their partners, you will either never find the partners or pay through the nose for them.