there are no genuine r4s anymore they are not being made,whats out there now are clones and there are around 14 of them,i dont know about the tt cards i use the m3 ds real and the acekard,a good place to buy is
you can pick your delivery type and its quick:rock on:
I try to stay to edge or supercards now to avoid the arm7 patching of each rom.
I know a site that supplys them for £20 + P&P (about £2) but car boot sales or computer fairs supply them too.
If you want the site then PM me and i will send it you.
I got a card from dealextreme and sometimes when i loaded a new game everything on the card dissappered,but was still on the sd micro card ,so I dont know if it was the r4 card or something else causing it.
I then got a card from http://www.r4cards.co.uk/ these ,paid £15.00 for it and no problem with it ,maybe a case of get what you pay for.