You may have a look at the Epson V700/V750. Very good price/performance rating and is able to scan 2 x 4 slides (6 x 6 cm) in a row. All of this for less than 1000 $. I use this scanner for a 2 years now and i'am very satisfied with the results. I also got the Nikon 9000 ED meanwhile. Yes the Nikon got more resolution, but if you don't need the resolution the Epson scanner is a good option for you.
Best regards
Pascal