HiFonics Titan TX-1505D would be good for those subs I think, can prob find a used one on ebay for your price range. Probably gonna have to push all the way to at least $150-$200 to get a decent sub amp of any kind though... even for 8" subs.
I once ran a pair of Kicker (old gold letter paper dustcap) 8" subs with a Kenwood KAC-920 and it worked out very well. Was equal to my previous setup, a single 15" Punch (old paper cone) sub with a LA Sound Laguna, except for the lower notes of course, the 8" cannot reproduce like the 15" could, plus I think the Laguna had more output than the Kenwood did. This was LONG time ago, but I am just saying all this because the 8" will sound excellent with MORE power. Get a decent sized sub amp.
I once ran a pair of Kicker (old gold letter paper dustcap) 8" subs with a Kenwood KAC-920 and it worked out very well. Was equal to my previous setup, a single 15" Punch (old paper cone) sub with a LA Sound Laguna, except for the lower notes of course, the 8" cannot reproduce like the 15" could, plus I think the Laguna had more output than the Kenwood did. This was LONG time ago, but I am just saying all this because the 8" will sound excellent with MORE power. Get a decent sized sub amp.