SN/LX MAD/BCN-DME €165-173/$181-190 ai rt (4.3-4.8 cpm)
MAD-BRU-DME-BRU-MAD €173 SN (4434 miles) 4.3 cpm
Sample:
http://www.kayak.de/flights/MAD-DME/...-01/2015-10-13
BCN-GVA-DME-GVA-BCN €165 LX (3812 miles) 4.8 cpm
http://www.kayak.de/flights/BCN-DME/...-01/2015-10-13