First, welcome to the forum. You've come to the right place.
Initial costs may scare you, but remember "Buy once, cry once." Basic set up will be keg, picnic tap, CO2 bottle, regulator. Pin lock (Coke keg) or ball lock (Pepsi), it doesnt matter. If at all possble, choose one or the other so you don't have fitting issues. If you do mix keg styles, my recommendation is to get fittings with the flare ends, not the hose barb ends. Makes it easy for change out. I have both style kegs, so I have flares on my fittings and hoses. When buying used kegs, clean with PBW, replace the lid, post and diptube o-rings. These should be available from your LHBS. If you need bulk, the o-rings are also available from Mc Master-Carr (no affiliation). A spare refrigerator will get you started with the above set up. Check out the CO2 suppliers in your area. Mine only does a bottle swap, so it may be more cost effective to buy the CO2 bottle from them and the rest from another source. Statring out, get a 5# CO2, however you may find that once you get into kegging a 20# is more cost effective.
Hope this helps get you statred.