Looking for a non-powered sub

Thanks, I`ll look into that.
Any $500-800 DIY subs out there that can compete with the better known commercially available ones?

Probably the best ever made is the Dunlavy Sub housed in the SC-V cabinet. Very rare, but worth the challenge of finding one. TIGHT deep base!

Out of curiosity, SCM, is there a reason that you specifically want a non-powered sub? Unless you have a spare power amp that you want to use, there are a number of advantages to having a powered sub: the internal amp is optimized for that particular sub; there is a built-in crossover (saving the expense and complication of having a separate unit); and cost.

If you need to keep your costs moderate, I'd suggest you take a look at the subs made by Outlaw Audio. Their subs were designed for them by Hsu, and they offer excellent value. For more info, go to this link: http://www.outlawaudio.com/products/subwoofers.html

I do have an amp that I want to use. It`s a Behringer EP1500.
I`m led to believe that to blend in a planar well, some outboard devices might do an overall better job.
Problem is, I don`t know what all I`ll need,and keeping the cost on the lower side of it all too.

I have a pair of Audio Artistry Dvorak subs. Each sub is a dipole sub, with one 10" woofer firing on the front and one firing on the back. They are a great match for planar speakers. I am driving them with a Hsu Research power amp with adjustable crossover modules.
I will consider seling them.