Yes, single mode optics are much more expensive than multi-mode optics.
But it also looks like the CDW link is for an XFP form factor when your data above shows you have an SFP device. The XFP is a larger size and not able to plug into the SFP slots.
I've had good experiences with Champion optics. But bear in mind that if you have optics related issues you will not be able to have a JTAC case if you don't have Juniper branded optics.
http://www.championone.com/sfp-10gbase-lr-10km-juniper-networks-compatible.html