I have bought all of my capacitors from Digikey.com. When buying, it takes a little extra time to pick capacitor value, brand, and size. They are definitely a reputable source as a large company with many customers. MacCaps.com has listings for many computers showing exactly what capacitors to purchase. In general, as long as the capacitance is the same between old and new capacitors, voltages that are higher than the original capacitors are fine. I would recommend sticking with surface mount tantalum capacitors in the A, B, and C sizes. (C is largest A is smallest) Anything smaller probably will not fit on the circuit board.