Well, it is clear the quad core would perform better overall, but for gaming? According to the latest "Best CPU's..." article, your money is better spent on a triple core @ $90.
For me though it depends on if you intend on overclocking. Let's just ignore the unlocking for now. The X4 you mentioned has a smaller cache but that doesn't seem to hold it back much for gaming. It has a good 3.0 Ghz clock speed, but the Phenom is 200Mhz faster. How much faster is that? Probably good for a couple of frames per second in games, not much more.
The quad will be better for multitasking and other computing tasks. The phenom will be easier to overclock.
The problem I have recommending the Black edition processors is you are paying for an unlocked multiplier. So unless overclocking is definitely in your future, your better off getting a CPU with a high frequency already and at least 3 cores for the latest software.
I believe this is why you don't see any of the Phenom II X2 CPU's in the best gaming cpu's articles. Because at a minimum currently you'll benefit from a third core, especially if you're doing much more with your machine than just games like most of us.
So if ocing is in your future, having a dual core at 3.5Ghz or higher is better than a quad @ 3.0. In your shoes, I would probably just make room in my budget for a X4 955 so I didn't have to compromise. However, if you are planning to OC you should plan on spending a bit more on an aftermarket cooler which will also affect your budget.
BTW, folks say you have a 50/50 chance of unlocking a core or two. I've bought at least three CPU's that were capable, but none of them have unlocked. Also I understand the latest steppings have disabled the feature. Bottom line: don't count on it! Be happy with the CPU as is.
I had an Athlon II x2 240 2.8 ghz and a Black edition Phenom II x2 3.1 ghz and used them on the same motherboard. When clocked at the same speeds I could tell no difference in performance while gaming or otherwise. When I ran any benchmarks the Phenom was barley any higher scoring, this maybe because the phenom only has a 512kb L2 cache per core where the Athlon has a full megabyte.
They both clocked to 3.6 ghz max to run stable regardless of whether or not I used the unlocked multiplier or FSB.
The Triple Core Athlon II I now have on the same system scored very slightly lower than these on some gaming benchmarks, but slightly higher on others probably because there is only 512kb L2 cache per core and no L3 cache. On any other tasks such as opening applications or other benchmarks it destroys both dual cores.
I have unlocked the Phenom on another system with UCC but that's another story, the cheapest triple was near £100 when I bought that 2 years ago so was worth the gamble. Now I'd just go for an Athlon triple as they are cheaper than a Phenom II.