For example a Seagate 600 Pro is double the money.
The Seagate 600 Pro is an enterprise-class SSD, and it's priced accordingly (i.e. it cannot be in the same league of Sandisk/Samsung).
I would argue it is a direct peer of these drives. It is an entry-level enterprise drive, set apart only by a couple cheap and negligible tweaks.
Just to get this out of the way first: in performance it's in the same category as the Extreme II, the Neutron GTX (which even uses the same LAMD controller, same as the vanilla-Neutron), and the 840 Pro (the 840 EVO can also challenge it), and it uses the same sort of flash memory (MLC, Toggle, 20-ish nm) chips from the same makers as those drives (bar Neutron vanilla and 840 EVO, present only as side notes). The 600 Pro chips may or may not
come from better bins, but you would more than likely have to have some really extreme data centre scenarios in mind - and years upon years to spare - to discover the difference.
The first cheap trick up the 600 Pro's sleeve, hard overprovisioning, is just a nice way of saying you've got a bit more memory, maybe more chips. Good for a gradual performance boost (but not enough to set the drive apart from competition, apparently) and longevity, but not super effective when you can't readily use that memory space for storage. This does not lift the drive above and beyond high-performance consumer-oriented drives, especially at 240 GB capacity (versus 256).
The second cheap trick, power loss protection (which essentially consists of adding capacitors and a firmware tweak, cheap as dirt), is a negligible fail-safe. In consumer (or even enterprise) operation, using a UPS or a battery-powered device (like a laptop, which are prime candidates for entry-level SSD use) can protect you in the majority of likely power loss scenarios where data loss might occur. To me it is a feature that should be on every drive as standard, like power loss head parking in HDDs - but how would they sell these enterprise drives and inflate profit margins if it was!
So that just leaves the 5-year warranty, which is also offered by the Sandisk Extreme II and the Neutrons GTX and vanilla both (woo!), all arguably consumer-oriented drives, and the 840 Pro, arguably an enterprise drive.
Right now the Seagate 600 Pro 240 GB is about £220, the Sandisk Extreme II 240 GB is £130, and the Samsung 840 Pro 256 GB and Corsair Neutron GTX 240 GB are £160 each on Amazon.co.uk (best deals for my locale at the moment). Curiously the Neutron vanilla at 256 GB is £145, way close to the GTX, and pricier than the Sandisk.
I brought the 600 Pro up as a contrast for a reason - you can get the same level of use out of all these drives with the same level of service (warranty), but the price on one is double just because they slapped an ENTERPRISE label on it.
PS. Toshiba is definitely on the table as well, being another big, all-in-house powerhouse.