For budget accomadation try Abdul's chalets on the larger Perhentian Island. Prices start at 40 RM, quite basic, but owners are friendly & beach is stunning, clean & quiet. It's also great for snorkeling & swimming. One down side, you're quite isolated & there are only a couple of places that serve beer, at a high price! Perhentian Islands are not really for partying, they are low key & for people who want to relax in beautiful surroundings. Still I loved it for a few days & would go back!
I would also go back to the Perhentian Islands in a heartbeat and have been going back almost every year.
I've recently returned from the Karambunai Peninsula in Kota Kinabalu, Sabah...the beach was beautiful, water was clean (but not blue as in the Perhentians) and as there is only 1 resort (Nexus Resort Karambunai) you get the beach virtually to yourself (the beach stretches about 3 kilometres...or more!). By far the best place to go if you REALLY want to get away from it all.
I just spent 11 days on Long beach on Perhentian island and I loved it so much, the people are lovely and the scenery is superb.
Not too hard to find places where you can be by yourself but at the same time you can find a party at 'Palm tree 2' pretty much every night.
I stayed at Panorama chellets for MR20 a night which is as cheap as you're going to get, pretty comfy too. The people there became to be my good friends and i was pretty sad to leave. If you do go please say hi to Shanon for me as i didn't get to say goodbye.
I know you have no real reason to trust me but i find it hard to imagine anyone regreting going there.
Cherating is nice also if you're going that way but doesn't have the crystal clear waters like the Perhentians.