I just discovered that the stock builds for the Thunderbolts -9S and -9SE both come stock with Double Heatsinks, and they don't appear to have a comparable price increase(i.e. they're not 1.5 million CBills more than the other two Thunderbolts). This means you can spend that same amount of money, for example, on the -9S and have it fully ERPPC meta compatible(minus modules). You can do the same thing right now with the -9SE even cheaper, buying only one Large Pulse Laser. Earning the Endo-steel upgrade allows you to install 3 more heat sinks, and make good even better.
That's probably one of the cheapest, most capable 'Mechs in the game right now, all things considered. You do still have to buy one of the variants with single heat sinks, so in reality, those two variants are the more expensive ones.
Also, I can disagree slightly with Kjudoon about there being nothing other than 'Mech bays worth spending MC on in this game. If you're budget limited, or very frugally minded(like me), that's very close to being true. I'd say the Hero 'Mechs are worth spending real money on though. They have a permanent 30% CBill earnings bonus, which is far and away a better deal than premium time, simply because it doesn't expire(and it also works in tandem with free premium time to grant a total of +80% CBill bonus earnings). Consider that if you bought a regular triple-A blockbuster title on a console, you'd end up spending $60 for the game. Buy the $50 MC package here, and if it's on sale, you'll end up with a tidy 14,400 MC. Also, if you suspect your first time buying MC will not be your last, you can save your future self some money by purchasing one of the larger MC packages.
I did the math, and the $50 package is at a sweet spot for cost efficiency improvements as you move up the packages. $49.95 gets you 12,000 MC(240.24 per $). Since the $29.95 package gets you 6500, or 217 MC per $, the improvement by moving to the $50 package is over 23 points more cost efficient than the next cheaper package. The next larger package on the other hand, at $99.95 for 25,000, gets you 250.13 per $, a less than 10 point improvement in cost efficiency. Even better, the additional expenditure is a smaller increase for the $50 package, than for the $100 package. There's a handy chart someone built too, if you're curious to know what things are costing you in-game later, after you've already purchased your MC:
http://homepage.usas...SDPriceList.pdf
Edit: The origianal thread where that chart is linked is here, and also includes a smaller chart with MC package price comparisons:
http://mwomercs.com/...132-price-list/
Edited by Throet, 23 December 2014 - 05:30 PM.