Those are a couple of good SLRs.
The MX is among the most compact and capable manual-focus Pentaxes, mechanically similar to the K1000 but with a bigger and more informative viewfinder, split prism, self timer and depth of field preview. It has many users and admirers on these forums.
The P30n is less highly regarded, but in my opinion it's generally underrated; I have one that gives me consistently good results and is a pleasure to use. It has aperture-priority autoexposure (which both the K1000 and MX lack) but can still be used in manual mode. Some shortcomings are that it won't work at all without batteries, and it is not possible to set ISO arbitrarily - you're locked at whatever speed is encoded on the film canister.
MX reviews P30n reviews
The lens looks to me like an older off-brand zoom, probably not of significant value. I won't comment on the dollar value of the camera bodies other than to say those vary a lot based on condition, salesmanship, and luck.
