Serviio

Have a DLNA blu-ray for main tv. I'd like to add DLNA device to second TV. Least expensive way to do it?

The absolute cheapest route, assuming you are talking about a finished plug-and-play product (there are kits as well) would likely be the Roku, or perhaps a Western Digital media player. However, the Roku requires transcoding most types of video files, so it helps to have a strong server running Serviio. In the same general price range is a Blu-Ray player, as you already know.

Sony and Samsung seem to do a good job supporting DLNA playback, although I've heard that some lower price Sony players don't have it, so be careful. I tried a recent Toshiba BD player and was disappointed in its performance. The user interface was slower than molasses. It also occasionally froze up playing a video. I've used Panasonic in the past with respectable results, but a less than satisfactory user interface. Maybe they've finally updated them.