I've been looking around too. Tom's Guide has an Analog to Digital article that includes tips about scanning slides. Here's a link:http://www.tomsguide.com/us/analog-digital-photo-video,review-1415.html
From what I have read in my search (I have yet to buy.) the cheap 5MP units you see aren't worth it.
Dedicated film scanners in the $100 to $300 range go a good job, but are slow.
The scanning services are just outrageously priced. Of course they may do some touch up for you, but $2 a slide and 1,000 slides, you can hire an out of work expert for a month to do it for you.
That leaves scanners with film scanning attachments. The Tom's Guide has some recommendations, but since the article is a year old all the models have probably changed. I'm pretty sure that route I'll go is to buy a flatbed scanner based on the tips in the article. I'll scan at 2,000 dpi and 24-bit color since I don't plan to make prints, just archive the images and view them on a monitor. If I find a special picture or two I would rescan at higher resolution/depth and then clean them up for printing.
Hope this helps. It is a frustrating search since there are many options and scanning film/slides is a secondary task that isn't very glamorous.