You should probablly look at a clan you like rather then a Leader you like as spending everything on a Leader can leave you with little for the rest of the cards and a deck with a Leader + not too good cards can have problems.
Well I'd say General Cr but with a 50000 budget it's probably Ongh or Dregn but then again if you want to build a proper deck I suggest you don't build around one specific card but rather build around a clan bonus.
Guru is way better than General. Also Korr. Anyway, you should just buy a half/full deck you like. Let's say, Mono-Junkz 25*, an unusual pick. FuzzQubikGibsonTremorhRomanaDreenVeenyle CrFlanagan. It works for Elo, you can switch Veenyle to Fizzle and Bam!, DT deck, Works for DM as well... A good, not-so-expensive and all-around deck that you could use anywhere. Consider it.