You'd probably be looking at the original R4 which is no longer in official production, or a DSTT. Try dscardworld or nds-gear.
The cheapest i have seen was for £5.42/$9.50 (not including P&P or MicroSD Card) There are too many r4 ds card in the market currently. The cheapest r4 ds card cost about 5EUR. But it only support DS and DS lite. The famous card is r4i sdhc 3ds. It support Nintendo 3DS,DSi,DS. So, I suggest you to buy a r4i sdhc 3ds card.
You cannot play DS games with the standard SD card; the SD card is too big. However, if you have a flash card (R4, SuperCard), you can store .nds games in your micro SD card. The flash card will be able to read the .nds game files and you will be able DS games.
Flash cards for the DS let you do a lot of things that the DS doesn't do on its own like play backup games, music and video. I can recommend the iEdge card for being good for a beginner. You can get one from dscardworld.com
maybe dust or the pins inside the DS are bend, or if you use a flash card, the ROM is broken/corrupted, ask Nintendo if it isn't a flash card/dust...
Yes, and you don't need a flash card.
Not natively, but you can get a flash card such as the R4 that will let you. Google R4 DS
no, but a team called komba are making a n64 emulator for dstwo. (a ds flash card)
TF is a abbreviation for Tiny Flash drive card
the cheapest ds is at barnsavers it is $20
loser!1
All ds flash cards are backward compatible so the iEdge being a DSi card will work find on DS Original and DS Lite. You just can't take a DS Lite card and put it into a DSi. You can find the genuine iEdge at repuatable vendors like dscardworld.
No, you cannot get a GBA emulator on the r4. Nor can you on any flash card. However google eZFlash, it's pretty much a flash card for the gba slot on the ds.