Alternative has those as well. Not keen on the figures with the lance leveled - project much too far (as with then rest of their figures with lances in that pose). Some of the figures I picked up second hand actually had the lances clipped...
I picked up 20 of their SC-11 with the upright lance for just that reason.
If you went with the Sarmation cav, you could also look at the foot bow - pretty basic archer in tunic and trews.
The number of Slavic tribes that did merge with the Bulgars during their early expansion is well covered in this video (use the closed caption option as the narrator does not pause between sentences). First Slavic Tribes www.youtube.com/watch?v=5Y4RbnZEOr8