I tend to use Dunlops, they seem to last a couple of years. I keep a good pair for work, when they split they become caving wellies. I've always thought that wellies with holes in were a bonus as they let the water out - none of that daft lifting the leg up to the bum business.
In the past I have used a pair of kevlar chainsaw wellies which were fantastic. The only problem (apart from the cost) was that they were incredibly difficult to get off - it required one person to hold me and another to pull.
Last time I was in Bogey Knights (well known Plymouth surplus shop) they had ex Fire Brigade wellies at about £15 - £20 a throw which look worth a punt, very heavy duty, steel toe caps and really useful looking hoops to pull the things on with