Try this:
=INDEX($C$2:$E$4,COUNTIF($A$2:$A$4,"<"&G2+1),MATCH(H2,$C$1:$E$1,0))
Assumptions:
1. Price table is in range A1:E4
2. Input number of user on column G, and term on column H (12M, 24M, 36M)
3. Put the above formula on column I which is for prices.