I did this holiday a year or two back and thoroughly enjoyed it. I can't remember whether I wrote a review afterwards but I'm sure there are some on the Forum - go into "Search" (top righthand corner) and then enter "Alpine Europe" (I think that's its official name), that will bring up everything that has been written. I can't give you any advice on how much money you will need - I took a euro money card - but you should remember to take some Swiss Francs with you since Switzerland (and I think Lichenstein) isn't part of the EU; you might get away with paying in euros for lunch etc but you would get any change in francs at a not particularly good exchange rate.
Bob mentions buying bottles of water. Something to bear in mind is that there is a Spar supermarket about 10 minutes' walk from the hotel (turn left on the main road in front of the hotel) which sells large bottles (or packs) of water for considerably less than if you bought them elsewhere (if necessary, decant into the small water bottle you will probably have brought with you on the plane from the UK) and you can also stock up on other things such as sun cream, biscuits, fruit etc there.
Something else to remember is that this is a very busy holiday - by the end of it I began to feel like "if it's Monday it must be Brussels" because we packed so much in and I began to lose track of where we'd been when. I wouldn't recommend it for anyone with mobility problems.
All that said, if you decide to go I'm sure you will have an enjoyable time.
Ann