Well, I'll get straight to the point. The current prices of equipment sucks.
Prices were fine until 0.2.0. Everything had a sane pricetag and was affordable at pretty well-balanced ranks. But now? The system makes no sense and is counter-productive.
Take the LRM20 Puma for instance. It's so cheap, that it can be used at the beginning of the match. Why? Oh god, why? What happened to the LRM20 Partisan? Oh right, it got more expensive. Why would anyone want to use it now? It's slower than the Puma, less armored, less maneuverable, doesn't have the point-defense Machineguns or TAG. Yet, a simple IS AA tank driven by an Combustion Engine is far more expensive than a Clan mech with an unholy XL reactor. Care to explain?
What happened to the Oro? It used to be a nice, fast tank that packed a medium punch. Now, you don't see them anymore. Too expensive.
The Timber Wolf? Why would you want a Timber Wolf? But the time it gets available, you can buy many of the bigger Assaults. And the fact that the Timber Wolf runs only 64kph instead of the 86kph like it's supposed to (same goes for Mad Dog) doesn't help compensating the huge price tag.
Osiris? Dirt cheap, and there's a variant with an AC20. A fricking AC20! This is insane at this price tag! It shouldn't even be able to carry that kind of weaponry.
Prices were fine, and now whole units have become completely useless. I hope this gets sorted out by the time the Mechlab is released.
My proposal: Use CBT prices. Yes people, MWLL is not CBT, I know that. Some of you will run in circles now, arms in the air, screaming the names of deities because I mentioned the ungodly CBT. But you know what? As far as prices are concerned, it was balanced extremely well.
You could have very cheap light mechs, even with a little punch (Urbanmech is dirt cheap and has a lot of firepower due to its AC10). There are a lot of medium-priced mechs that are very good (Warhammer, Marauder, Rifleman, etc). Even the Atlas was kinda cheap, all things considered. Then came the Clans. With them, XL reactors, and suddenly you could pack a lot of firepower, armor and heatsinks into a small package. These machines are far more expensive, but very well worth it.
So, what's the point? It's simple. The engine has always been by far the most expensive part of a mech.
Combustion Engine: Dirt cheap, but won't really move anything beyond some tanks
Fusion Engines: Quite expensive and very heavy, but move mechs easily
XL Fusion Engines: Extremely expensive with a medium weight, Best ratio of weight to power
The player may choose. Only the XL engines allow for highly-optimized mechs that pack everything from speed to armor and weapons. The catch is the fact that XLs are godawfully expensive. Clan tech should be far more expensive than IS aswell. After all, it is superior, and Clanners need fewer mechs to achieve the same goal. Well, make them pay for it! Instead of balancing IS and Clan mechs to be equally good, balance the prices so by the time IS uses heavies, Clan will use mediums.
Make them pay for the best machines! Few, rich players can move around with highly-optimized mechs and the majority sticks with Fusion engines. This would reduce the number of overpowered variants on the battlefield, increase diversity and introduce some saner variants.
What I mean by that is the fact that once the Mechlab is out, I don't expect anyone to use anything but the biggest guns. AC2? Bah. Small laser? Useless. MGs? Nah. LRM5? Don't make me laugh. Nobody would use those anymore, why would they want anything below an LRM20 or AC5? If mech chassis become restrictive because XL engines are just so fricking expensive, we will see more of those smaller weapons and less machines optimized up to the last bolt. And lets be honest - don't you miss the times when your light mechs just had some medium and small lasers to plink away at each other instead of huge AC20 cannons? Nobody want's half a team with Novacats and the other half in Vultures because they offer the best price/firepower ratio, do they? This is stupid. Or consider the Quad UAC20/Gauss Assaults that will undoubtedly pop up when the Mechlab comes out. I'm dead serious here.
disclaimer: Please don't rip my head off. I know it's a beta. You don't have to point it out. I know that all is subject to change, this thread is merely to write my own ideas down.