The main problem with Offa's Dyke is that there is simply not enough accommodation. Only 2 youth hostels close to the path (St Briavels and Kington). Others like Clun and Capel-y-ffin (soon to close) are off the path, and unless you're with a large group, much of the accommodation is pricey if you're travelling alone. It is a path that's probably best done on a circular route or with transport at either end.