I'd choose the
1) NHT (10 " sub)
2) Aperion including their (Dual 8 ") sub
3) mix and match - never liked the ideea IF I can avoid.
With 1) or 2) you have the advantage of "same look/ they look good togheter" which to me it matters.
Also try talking to NHT to replace to 10" sub with a 12" one and you're done

OR talk to Aperion to throw in a 12" instead of dual 8"
You might have to pay 100$-150$ but still you'll be in the 2k$ budget