some good info posted already PG3.Just to add a 'lil,yes,prb is cheaper to shoot if you're buying your bullets,but if you cast your own the difference in cost is not alot between prb and conicals.Lead is dirt cheap and often free for the taking,beware that wheel weight lead is not pure lead though.It's harder and some guns won't shoot it well for a host of reasons,as well as it won't expand as well on game.Heavier conicals also require heavier powder charges so again the cost of powder increases by anywhere from 30- 50% vs. shooting prb in some cases to acheive the same accuracy/velocity etc.?
Don't think you could go wrong with a Lyman GPR in .54,either cap or flint.Solid reputation and slower round ball twist,with a fair bit more downrange energy than a .50cal.>50s,even with prb will cleanly take deer size game,but a .54 is something to consider if bigger game might be a possibility.(Quebec moose?)Be aware that the Lyman GP Hunter is a different animal than the GPR and has a faster twist,1:48 I beleive?The 1:48 is also standard on TC Hawkens,both flint and cappers,and is considered to be something of a compromise twist that can stabilise both PRB and conicals adequately.Stay away from faster twists like 1:32 and faster etc. found in modern in-lines and some repro guns,they're designed to stabilise sabots.