Obvious alternative is the slightly more expensive Asics 2170 model, that you may be able to pick up cheap in the sales. The other alternative in the Asics range is the DS Trainer that is a lighter trainer but with the same support as the 1000 and 2000 series.
Alternatively, any mild support shoe from the various other brands should be fine. Although, as seren nos said, if you get on with the asics 1000 series you may be better sticking with them. It can be an expensive & sometimes painful experience getting the wrong shoes.