Look at this link. http://wbo2.com/
Aussie company.
I have the 2AO kit, WB sensor and seperate LED AFR display, was around $400 You can buy the various Bosch Wideband heated sensors through this mob at a lot less then you would expect to pay elsewhere. My WB sensor was less than $100.
AUD$300 gets you the new compact 2EO DIY AFR meter kit with sensor. About $150 more for a pre-constructed unit(they are a very complex kit to build). Best value in town IMO.
I don't even think the EMS uses a fully wideband system O2 system. It's a the old LSM-11 sensor which realy aren't true WB. The new WB sensor are so much more cheaper and much more accurate.