i also tried both yesterday, before i posted the message. one replied, one didn't. the one that did, didn't reply to my follow-up question, if u get me....my question was in english, their reply was in german --> i figure they understand only french and german.
the one that replied (tarahist) wanted a minimum booking of 150 swiss francs (about 60 pounds i guess), hence my request for something cheap. 90 francs of that was for the invitation.
what is doubly frustrating is that swiss don't usually need an invitation at all. embassy seems to be hassling me cos i won't have my own vehicle. do you understand german? if so, check out www.sahara-info.ch
it is a little more open to travellers without their own vehicle.