I posted about this about 3 weeks ago, but can't remember where.
So, to summarise:
Nikon manual SLRs are wonderful, built to a terrific standard, BUT, because of this they were the professional's camera of choice, so second hand models may well have been VERY badly treated, so purchase with extreme care.
The same applies to Canon, but to a lesser extent, I think.
Minolta tried desperately to gain the same sort of reputation, and made a lot of gear that was as good as, sometimes even better than, Canon and Nikon. Because they never quite made it to the top in terms of street cred, their equipment is often in much better condition, yet much cheaper. Minolta is my system of choice - I have spent about 250 dollars recently, and got 2 bodies, a 24-70 zoom, a 50 mm 1.7, a 28mm 2.8, a 100-200 zoom, and a flash gun. All are in perfect working order, most are in mint condition. I rest my case...
When selling SLRs in the late 60s and early 70s, we felt that Pentaxes were a bit tinny - good lenses, but increasingly poor materials. I liked the K1000, but can remember the shop manager repairing a Pentax by BENDING the door straight, after a customer had dropped it while open. Ok, it then worked, but I would prefer a camera so well built that it didn't bend in the first place. (I had a Topcon that chipped our concrete floor when I dropped it, but still worked...)
Olympus were very "pretty", lots of bells and whistles, and so LIGHT. And so FLIMSY, in my opinion. (nb, I am talking about the very early Olympus models, I don't know the OM40)
Early adopters of the then new wave of electronicified cameras were often disappointed with their reliability, but obviously that must have changed as time passed. Again, with electronics, purchase with EXTREME care - it is easy (ish) to get manual problems fixed, maybe even at your local camera club. But a printed circuit board that is broken may well be irreplaceable. Furthermore, cameras relying on electricity for wind on etc, may well just not work if the batteries or the circuits die.
My 2 Minolta X300s will blithely carry on no matter what - I may be guessing the exposure, but at least I will get a photo.
As to what to buy in terms of lenses etc, I recommend:
A manual SLR body, with an f1.7 or f1.8 standard lens. Portable, fast lens, carry it always.
A 28 mil 2.8. Landscapes, architecture, group "portraits".
A 135 or 100 mil lens. Individual portraits, medium telephoto, sometime nice for macro work.
A decent flashgun. Get one that can be used off-camera somehow, with a slave unit or long lead.
UV filters for all your lenses, and a polarising filter for every filter size you have.
That will do to start with, and might cost as little as 150 dollars. A good idea is to seek out complete packages, as these seem to sell cheaper than separate items.
Later you could get a sturdy tripod, a long zoom. a filter system to play silly beggars with (Cokin are cheap and easily available on
ebay), a wider wide angle (20 or 24), more flashguns, a motor winder - the list is endless, there is always something cheap and fun to buy.
Good luck, and as always, don't forget to post opinions and results here.