There's a group buy going for Bulk Reef Supply on the 29th of this month. You can usually save some money on a unit. Group Buy
I bought my RO
from BRS and they have been great. They offer good technical support as well.
Another option is Aquatic Life offers refurbished products. They are changing there website right now and don't have a refurbished section on there website so you have to send them an email to see if they have any refurbished products, it never hurts to try. I've bought 4 refurbished LED
lights from them for quite a bit off retail and I haven't had any issues with them.
You may be able to get a cheaper unit from ebay but you're not going to get the customer service if you have questions or warranty needs. The filter size may be odd or hard to find also.