Building a niche email list with solo ads

Hello there,
I have a internet marketing youtube channel, website and email subscription list that I started about 6 months ago and I've been seeing somewhat decent results.

My investment so far...

-GetResponse ($15/mo)
-Tweepi ($15/mo)
-Unfollowers (($17/mo)

Total is $47/mo X 6 Months = $282

My Results...

Over 6000 twitter followers, almost 500 YouTube subscribers and over 15,000 video views (search "yimmy worldwide" on YouTube if you want to check me out. Haha!) I know these numbers could be better, but I'm learning and I'm also increasing the quality of my content as I go. This was only going to be a test, but since I'm getting some traction I want to fuel the fire a bit more.

I use a auto dm/auto tweet technique to drive people to my YouTube channel and my channel drives people to my squeeze page. I have been able to get almost 500 subscribers, over 100 email addresses and I've even sold some of my own digital products which was very surprising for the amount of effort and money I've put in so far.

Now, I want to start pumping some money into solo ads to really build up my list but not sure who is legit. Does anyone know of a good solo ad provider that can help me build a IM niche list?

Huge help if anyone does...

Cheers!