Brickpicker's database is full of historical eBay sold listings, but it's also important to find out what was just sold in the last 5 minutes. Click the link below to view eBay's latest sold listings. When you look at Brickpicker's data and see what sold today, it can help you to see if the sets you are interested in buying or selling are developing an upward or downward trend.
View the Latest Live eBay Completed Sold Listings
I would not recommend to buy this as investment, unless you get a good discount - in which case you should be able to sell for that profit almost right away. Don't think long-term for these sets.
However, if you plan to use it, and you are somewhat interested in building and programming stuff, this is a great toy. The brick runs Linux, and you can (although not officially supported) even run your own OS on it. It has a USB port for endless extensions, and a micro-SD-card slot for addi...