some strongman equipment is easy to obtain at minimal cost. You can acquire large used tires free from any heavy equipment dealer, or tire store, and the will usually even deliver free of charge because it actually costs them to recycle the tires. Take your old gym bag and turn it into a giant sandbag, then you could usually get empty kegs from a local bar for $30, that is what the deposit usually is on them. You can use an old tire, 2x2 piece of plywood,eyehook and some rope to make a decent sled.
As far as in the gym, i recommend heavy deadlifts, squats, hang cleans, and standing overhead presses. Shrugs, are always good to throw in there along with good mornings and lots of core work. One of the biggest things is to train your grip, if you are intending on competing in strongman a weak grip will definately affect your performance.