I wanted to know if it is a good idea to get some FGPA's and use them for scrypt mining . How are the hash speeds now on recent FGPA's and what would you recomand ?
In short,
NO.
Some (rather inefficient) open source code for scrypt is available on my
github. It gives around 15kHash/sec for scrypt on a LX150 device as used in the majority of the bitcoin FPGA miners, which is not really worth the effort (and I'm not providing any ongoing support for the code).
Beekeeper has some slightly more efficient proprietary code for the
devices that he is selling, but IMHO these are not really worth the investment. ASICs for scrypt are coming (or in the case of GridSeed, have arrived) and FPGA is not well suited to this POW algorithm.
You may want to consider mining
Blakecoin on the LX150 based bitcoin mining boards as this algo is much more FPGA-friendly, and may be profitable if you already own the kit and it's just sitting idle, though it's probably not worth investing in purchasing new hardware.