The other day, I picked up a new Matchbox truck, which is a mobile X-Ray scanner, named the "XCanner", looks perfect for use at a Spaceport, Airport, or SeaPort, for your ultramodern through Sci-Fi Periods.
It's a large white truck, with a yellow, L-shaped bar, to represent the scanner, and it says X-Ray on the side.
Another nice addition to any tabletop for only 99 cents.
Also, at the local pet store (Petsmart, I think), they had hollow "rocks", which are smooth and gray, like river rocks, which look like they could be used for a primitive alien species' home. There's a roundish/ovalish hole in the side, and bottom, so you can have two different looks for the smaller ones, and there are some larger ones too, for use with larger scale minis, if you need that.
About $2.50 USD for the smallest ones, and quickly escalating in price for the larger ones.
Also priced plastic plants for aquariums, and the cost for those was off the charts. Some were as much as $20 USD, and many/most were $9 USD or more.
Crazy, for 25 cents worth of plastic.
Need to look again at Walmart, and other discount stores, I suspect.