First, remember that there are at least three different kinds of AR carry handles. First are the ultra cheap Chinese knockoffs you see for about $35 and should avoid.
Then there are two different height US made CHs. The proper milspec height is used on Colt, BCM, Daniel Defense, Noveske, LMT, PSA, Spikes and others. This also is the same height that you see on most third party flip up sights like Troy, Magpul, BCM, MI and others. All these rear sights expect the proper height F-marked FSB or third party front sight. F-marked means flat top or M16A4/M4 height.
The second height for US made CHs is 0.04" shorter than milspec. Often it's called commercial height or A2 height and is used on DPMS, Bushmaster, ArmaLite and others. Depending on your front sight this may be the height you want. A2 is the same height as the old integrated carry handle on the M16, M16A1, M16A2 and M16A3.
Proper carry handles made at US forges like Cardinal, Anchor Harvey, Cerro Forge and others tend to cost from $80-135 new. Used ones can be found, even on eBay for around $35 but you have to make sure they're not knockoffs or the wrong height.