fameslee:
The cost in the long run depends on yourself. You can spend less than $100 on any particular Wizkids game and get yourself a good size collection to play with, either through boosters or buying singles. There are plenty of shops that sell singles for reasonable prices and you can assemble a good army for playing with.
Where it starts to get expensive is if you get hooked and "gotta catch 'em all." Also, if you want to compete in tournaments you'll need to spend more money in order to be competitive, but that's the nature of the beast. If your intention is to just put together some armies and play a pick-up game once in awhile, then it's not that expensive.
Just like any other collectible game, new expansions will add new rules to the game to keep it interesting. Wizkids has done a decent job keeping "power creep" under control, at least as far as Mechwarrior is concerned. They try to keep their sets balanced with each other so as to minimize the number of old pieces that are made obsolete by the new rules. So it is possible to compete with the new stuff using old pieces. Of course if you want to play with the new stuff then you'll have to shell out more dough. Wizkids also makes it a policy to never ban a piece from tournament play.
As far as the randomness, yes this does turn some people off of the game. Me, I'm a junky so I don't mind so much
Having said that Wizkids has recognized that there are people out there who prefer non-random packaging of figures. Their latest offerings (Crimson Skies and Shadowrun) are what I think of as "semi- collectible". The basic set of figures come in preconfigured blister packs and you see what you get. With these games you can buy what you want and not worry about getting stuff you won't be playing with. How they make it collectible is through the release of limited edition figures that can only be won at tournaments or through other promotions.