fans are what i have had to replace on each macbook my partner has owned. that and power cables fraying (they do not replace those for free in chile, so we've been through one expensive power brick after another...).

by the way, for power cables, i have, finally, found a solution: use silicone sealant (the stuff you use around the bath) to make a cable strain relief. it doesn't look that great, but it works. splodge sealant on the cable where it leaves the plug and smooth it out along the cable. the sealant should join the end of the plug and taper out over a few inches of cable.