There's a few out on the market! Moroso, Hurst (~$299), B&M (~$110), TCI (~$170)......
I reckon the cheapest and best one is the Biondo model (it's identical to the moroso unit).......after all, it's only a hydraulic solenoid valve.....this one is plane and simple and does the job. ie: the Hurst one looks schmick but has a schmick price tag too! I just bought a Biondo one and will be fitting it in the near future. Simple in/out on the brake line and a 2 wire (+/-) hook up. You can get rebuildable kits for these ones if you ever need to in the future. Just need to fit your own switch and fuse.
The Biondo & B&M ones go for about $100. The others cost a fair bit more.
These guys rip you off but you can find cheaper.
Biondo
http://www.vpwmailorder.com/asp/product_page.asp?sub_cat_id=1296
Hurst
http://www.vpwmailorder.com/asp/product_page.asp?sub_cat_id=946&manu_id=
TCI
http://www.vpwmailorder.com/asp/product_page.asp?sub_cat_id=918&manu_id=
I got mine in the US for US$40 bucks! Giddy up

I brought it back in my hand luggage.....the xray machines went crazy.....thought I as some freak with a bomb! Try explaining what a line lock is to some gomer security guard.....scum bags made me miss a connecting flight until they could find someone in the airport who could identify what it was!
Cheers
AdrianXD