According to a well known subwoofer reviewer: The Monoprice 9723 at $99.99 was the best budget subwoofer of all of them. It's $99.99 on Monoprice web site but they are out until next month. You would have to buy it on Amazon at $141.00 which is still a good price.
2nd best subwoofer on his list was the BIC America V1020. It sells for $169.00 on Amazon and Best Buy web sites.
There are plenty of others but these were his recommendation's.
(Living Room) Sony XBR65X950G 4K TV, Harman Kardon Enchant 1300 & HK Enchant subwoofer, Sony UHP-H1 SACD & Panasonic DP-UB420 4K BD players.
(Garage) Sherwood RX-4105 Receiver, Samsung DVD/CD player, Klipsch 2.5 med oak speakers