Cost Effective Sub Woofer

Interested in obtaining a cost effective sub woofer for a reasonably good sounding two (2) channel stereo system consisting of the following equipment: Monitor Audio Gold 100 speakers on monitor Audio stands, Rotel Integrated amp, Linn Basik turntable with Rega Exacta 2 Cartridge, Kimber Speaker Cables and jumpers, Interconnects and digital cable, Marantz 5004 CD player, PS audio Power Cords. The music room is not treated and 17 x 24 in size.  Any suggestion on a sub woofer. Prefer to stay under $1000.00. Listening preference is jazz at moderate volume. Not loud at all.