Once you have the MX you probably won't be using the K1000 much!
The K1000 just strikes me as being hair-shirted. Any SLR with full manual mode is perfectly acceptable to learn photography with, extras like a self timer or a switch to turn the light meter off are hardly cheating. Why deliberately make life harder, especially given the prices good K1000s go for?
I started with a K1000 as in a pre-Internet age I didn't know what other Pentax bodies were out there. Now I'd suggest a KX or MX for a beginner wanting a fully mechanical SLR, or a P30 for someone wanting to try film.