I have recently used buy4ds.co.uk and they seem fine, though I have got a dodgy GBA+Exploer 2in1 card, which they will be replacing when they have more stock, so if you are after one of those as well I would enquire if they have them first.
I have noticed that their prices have been raised recently:
'Due to approaching Chinese New Year, the supply of all sorts of flash carts for Nintendo DS becomes tighter (not only DSTT). Our supplier increased the price so we put up the price a bit and only have limited DSTT for sale. After 18th February 2008 the price will come back as normal. '
DSTT CART + 2GB Micro SD card (made by Integral) + USB Micro card reader, supplied with latest DSTT Kernel, and Moonshell can be installed if required, all for £33 + £2 P&P, tested before dispatch, pay using paypal or pppay, and it will be shipped out 24 hours after cash has cleared via royal mail 1st class.
I have used http://www.ds-memory.net/dstt_details.php. Not the cheapest but communication is good. Originally ordered a R4 DS but received a DSTT instead; I was annoyed at first but after using the DSTT all was forgiven.
I got mine from www.mobymemory.com
This came with 2GB card (Sandisk)
Cost £37.99 + P&P ... however, if you spend £40 p&p is free. So you're better off doing what i did and ordered something else cheap to bring it to just over £40.
Good thing as well is that generally, if ordered before 3pm it'll come next day. My items always have - although with recorded delivery, they say it can be up to 5 days.
Hey, i ordered a DSTT from http://buyr4ds.co.uk/ yesterday and it arrived this morning.
It was £28 including VAT, around £30 for next day delivery as well.
They answered my e-mails within half an hour every time.
I really recommend them, fantastic company.
my old MX518 also had the rubbery coating starting to come off, i can never get it back to un-sticky state, the harder i clean it the worse it seems to get, same thing with the wrist rest on my old keyboard too