I signed up for Sellbrite just over a month ago after paying a similar cost for another sync program that took over 24 hours to update and sync. Needless to say, Sellbrite syncs sales across all channels FAST so you don't have to worry about overselling.
The benefits from using Sellbrite not only include freedom from worry, but you'll also save time. You can list directly from Sellbrite to all channels and not have to jump around wondering if your products are where you want them.
Another benefit is cross marketing. For example, I use Etsy, which limits the type of items I can sell. I wanted to share those products elsewhere - Sellbrite allows me to do this easily. As a result, my products are viewed across more channels - more views means more sales. I saw more sales almost immediately – this is the biggest benefit by far. So, if the cost is off-putting, consider reorganizing your marketing budget to include Sellbrite as part of the plan - it will make a difference in your monthly revenue.
Listing and importing inventory is easy, but you really must understand your channel attributes to make the most of using Sellbrite. Channels are constantly changing and Sellbrite seems to stay on top of the changes as far as I can tell.
I've used customer support several times and the support is lightening fast and attentive. My questions are always answered in a timely manner (even weekends) and I've never felt misunderstood or irritated with communication - that's a big deal - you want to know you can count on someone being there to help if you need it.
Sellbrite is an excellent choice for the small business owner who wants to grow, but still remain in charge - you'll benefit from less worry, more time, cross marketing, and, most importantly, an increase in sales.