You'll have a hard time finding people looking at 256GB SSD because very fast drives are in the $700 - 800 range. You can find
this drive for $749.99 which can almost match Intel's controller performance.
SSDs now come in two varieties. Lightning fast (RunCore custom Indilinx controller, Intel controller, or Sandforce controller) and very expensive or acceptable performance and moderately expensive.
You asked about the "best deal" on a 256GB SSD choosing large space with moderate cost/performance (compared to the lightning fast SSDs) and were pointed to large "big box" retailers such as Newegg.com and Amazon.com as well as deal hunting websites for additional coupons.
I have used SSDs since 2008 and I can safely say that I would
not buy an OEM SSD again. The performance of the SSDs will drop over time without garbage collection (OS X does not support TRIM at this time and we don't reasonably expect it until 10.7 or a very late 10.6 update) which OEM SSDs rarely support.
After market provides a better balance of cost, performance, and features.
In short, speed space and cost: pick two.