If by compact you mean lightweight, the lightest tactical type scope in the 3-9x range with exposed turrets and mil/mil that I know of is the Leupold Mark AR mod1. It's 12.4 oz. the 4-12x40 version is 14.8 oz. They are in the $350-450 range.
For little cheaper, the Midway Weaver GS 3-10X40 is excellent for the money and comes is at 16.6 oz.
The leupold VX-R Patrol looks nice also, 15.3 oz., and illuminated Tmr reticle for around $600. The Vortex 2.5-10x32 and x44 are nice too, but are getting over the 18.5 oz mark, and on the top end of what I consider compact and lightweight. Everything considered, if I had the funds I'd probably jump on the pst 2.510x32 for around $800