Hi there
decent cheap(ish) SSD drives are available now with affordable prices for the 256GB models. 512 GB Models are available (but still relatively expensive).
The day of the spinner for home use is rapidly coming to an end -- for commercial servers etc high end SCSI disks will still be available for a long time yet - but expect to see the writing on the wall for small 2.5 inch laptop spinners -- BTW with a SATA==>USB adapter these old laptop disks make very good "Backup devices" or things like Music / Photo / video backups and you will soon be able to pickup 320 GBP one's for around 20- 30 USD !!!. 500GB and even 1 TB disks of this size and format are available as well cheaply.
I'm using a 320GB old laptop disk split into two partitions -- small one for an OS and a 2nd one for two Virtual Machines. I run (I know it's a W7 Forum but it's a USEFUL TOOL) a Windows 8 to Go system on the disk plus I have two virtual machines.
I plug the Disk with the SATA==>USB cable into a USB3 port on the laptop --even though the cable is a USB 2 one the disk performs better on the USB 3 port. I'll swap the USB cable for a SATA==>USB3 cable which will improve performance more - even when you plug a USB 3 device into a USB 2 port.
The Windows to go is a fully functioning WINDOWS 8 system that runs directly from the HDD even if there's no functioning disk in the computer it's being booted from. It's NOT an INSTALL or RECOVERY system. You can with a bit of work make a similar W7 system but it's not for the faint hearted.
The other way people made portable OS'es was to create a VHD and mount and boot the VHD (Virtual Hard Drive) but this generally needed at least a Boot drive on the computer. The Windows to Go type of system doesn't require this - and if hardware drivers are needed then at boot it just finds and downloads from the web --very useful tool too.
The SSD's I'm using are the SAMSUNG 830's --excellent SSD's all round.
On Acer Aspire V105 11 inch laptop with the i3 processor (so not the most powerful processor) the WEI for the SSD is 8.9 (it's running W8 and on W8 the WEI scale is 1.0 to 9.9) so a VERY creditable score for that laptop.
That same SSD would yield well over 9.0 if fitted on to some more top end gear.
Processor and memory probably slow down the WEI a little --you can never test things in isolation -- but I'm VERY happy with the performance gain the laptop has by swapping the slowish spinner for an SSD.
Cheers
jimbo