Anyone used this TDS meter?

Just wanna know if anybody can comment on the long term accuraccy of this meter http://cgi.ebay.co.uk/THE-BEST-TDS-...286.c0.m14&_trkparms=66:2|65:15|39:1|240:1318 manufacturer states it's ideal for commercial use so I'm guessing it's at least reasonable.
Grown 4 crops now just by winging it and got decent results but i reckon it's time I got one of these to fine tune my feedings. Any better meters in the UK that I should be aware of before buying?
Thanks everyone!

I have one of these and it works great. I don't know what the life expectancy of it is since I just got it a couple of months ago but it appears to be well made, especially for the money.

I have one and it has remained totally accurate for 10months. Dirt cheap aswell.