My choice for accessories is the Lionel 22980 SC2 Switch Controller. It can be programmed for six accessories and is readily available on the used market for less than $100. I see a bunch of them on eBay, and they pretty regularly come along in the OGR for-sale forum as well.
You can also use the Lionel 81639 LCS-ASC2 with your BASE1L, you will need the LCS DB-9 Cable/power supply. One advantage of the SC2 is it picks up the over-the-air TMCC signal so you don't need any wiring to it for serial data.