Hey,
Buggy safari was brilliant and I would well recommend it to you. The person doing the driving needs a driving licence. It cost for one buggy, with me and the wife both in it, 110 euros, but they recommend the extra insurance for another 20 i think it was. 130 all together we paid. i think its 90 if your in the buggy alone. we were told as it says on their site long trousers and closed footwear, but we turned up in tracksuit bottoms on a sweltering hot morning to see everyone else in shorts!!! lol. Buy yourself something to cover your mouth, we bought bandana material. as you will be eating dust the whole way round otherwise. and dont park too far away from the place like we did. we had to walk about a mile back to our hire car looking like i dont know what, sweltered and plastered in dust.....
Bring water with you as you stop a couple of times. half way round you stop for a break in a large set of sand dunes, and you get to go a bit mad here. pretty cool.
I would recommend emailing them, or through the form on their site, eventually booking the day we wanted. all they need is where your staying and a contact number, and it was pretty straight forward once we arrived then on the morning.
Cant help on the quads as ive never tried them but the buggys are deffo worth the cash.
hope that helps ya..
PS, i have a few pics from my buggy trip here......
http://flickr.com/photos/30772055@N02/page3/jake