OCZ Technology Group's Core Series 2.5" 64GB SSD (Model OCZSSD2-1C64G) was right up there as one of the two cheapest drives I could find online. While it retails for US$269, Newegg.com had it listed at $169 with a whopping $100 rebate. The Core Series SSD has an OK sequential read rate of 100MB/sec. and a sequential write rate of 80MB/sec.
This drive had a number of bad reviews online regarding reliability, so caveat emptor. But, this was also among the lower cost drives with the large rebate, so it may be worth investigating.
While investigating internal SSD drives, I came across a rather unique method of adding flash memory to your PC that you may want to give a try -- the Addonics CompactFlash Adapter.
Addonic's flash adapter
Addonics Technologies offers two versions of its CompactFlash Adapter, a single-card adapter and a dual-card adapter. The interesting thing about these adapters is that you can upgrade on the fly by adding higher-capacity compact flash cards. For example, about the highest-capacity compact flash card you'll find today is 16GB. Using a dual adapter, you could achieve 32GB of capacity in your PC. "For the ordinary user running Windows Vista or XP, where you'll be storing a lot of data on the hard drive, you may find this not enough capacity for you," acknowledged Bill Kwong, president of Addonics. "The advantage we have is that the customer can buy whatever media is available and make their own solid-state disk drive."
However, Kwong notes, if you're an ultralight notebook user or you're converting an old notebook to run specific applications but not for storing a lot data on the drive, this adapter may be the way you want to go. It creates a lightweight alternative to a hard disk drive, and it does consume less battery life than a traditional drive, though the advantages may be negligible, because a monitor and CPU use far more power as a percentage of overall use.
Kwong also said that Addonics plans to come out with a six-slot adapter in the next 30 to 60 days, which will up the ante considerably, but it also ups the price. CF cards range wildly in price up to US$200, but I found an A-Data 16GB card sells for US$34.99.
Retail prices for the CompactFlash Adapter are quite reasonable: A single slot with SATA interface is US$31.99. A dual-slot SATA adapter, which can also mirror data between cards for added security, costs US$79.99.
So doing the math -- if you purchased an Addonics dual adapter along with two 16GB cards at US$35 each, you've got a 32GB SSD disk for US$140. Not great, considering you can purchase many 32GB SSDs online for about the same price or less, but hey, it's another way to go, and it does offer some data redundancy.