I managed to sell some NFL Legits and momentos tonight so with the proceeds from that sale I purchased some collection properties and with it I was able to complete the Oaklawn, Dallas collection.
This collection needs 3x properties to be completed, and get a one-time 2,500 UPX bonus back after 7 days which helps to offset a little bit of the cost of the properties.
Once completed, the collection gives a 1.6x boost to earnings I believe although I'm unable to see if presently with the image shown the way it is.
Collections give a nice little boost and typically hold their value much better than generic properties so these are always a good addition to a collection.