The Epson Perfection 4490 Photo, as you say, can do 4 slides at a time but with auto file naming set to your chosen directory it is as fast as shelling peas.
It automatically detects and crops to the exact 35 mm frame. If you are sure the slides are the correct way round ignore the preview option and just press scan.
Once you have got your routine going you can read Answerbank and scan at the same time.
For your price range I think it is great and as you probably are not going to be taking any more 35mm film you will see get hundreds done.