Launched 5 months after the P67 and H67 chipset the Z68 chipset combines the advantages of the H67 and P67 Chipset so that overclocking, dual dedicated graphics cards and use of the integrated CPU graphics is available. Whilst on the surface it would seem that this would be the chipset to go for, how many users that have 2 dedicated graphics cards will actually want to use the onboard graphics when they already have 2 more powerful graphics cards in their system anyway?
The only real advantage is for users that wish to access the HD graphics features such as quick sync, but considering it’s only supported by very few transcoding programs and there are not many people out there that need or will want to transcode, it makes it almost pointless to choose Z68 over a P67 chipset.
Same applies to users that want to overclock the CPU but use the onboard graphics card; it’s a very limited market.
Finally, another feature of a Z68 chipset is known as SSD caching which is where it allows the use of a small (say 10 or 20 GB) Solid state hard drive to act as a cache for a larger ‘traditional’ hard disk. If you are already planning the use of a Solid State drive this feature is redundant.
If you can’t afford a decent size SSD (40GB+) then there are more cost effective ways around using a small SSD and SSD cashing like spending less on a motherboard, (H67 chipset or even a P67 chipset) and putting the saved money into a decent size SSD.
Given the above, I'd save the $50 .... there's also dozens of Overclocking guides specifically for that board which tends to make life easy.