I was recently having trouble finding some too, a post in the CNC forum yielded speedy help. If 1-1/8" will do the trick, here is the one I got on Ebay. This seller has a very good selection.
https://www.ebay.com/itm/1-8-1250-2-FLUTE-LONG-FLUTE-1-125-CARBIDE-ENDMILLS-FOR-WOOD-OR-PLASTIC/152448862060?_trkparms=aid%3D111001%26algo%3DREC.S EED%26ao%3D1%26asc%3D20160908105057%26meid%3D4bd1f b4af2544c0a9fc602a74117e9d8%26pid%3D100675%26rk%3D 1%26rkt%3D15%26mehot%3Dag%26sd%3D152448862060%26it m%3D152448862060&_trksid=p2481888.c100675.m4236&_t rkparms=pageci%3Af6adc382-74b7-11e8-84bd-74dbd18081fe%7Cparentrq%3A1e760bad1640acc79ddfcc46 fffe6459%7Ciid%3A1
I see the post was moved from General to here.. My RSS feed didn't.