I prefer glass to acrylic. Unfortunately, as jexnell pointed out with acrylic, glass tanks have also hiked their prices in the past year. I would not expect the costs to go down anytime soon or ever for that matter.
For a new 180 at the best price, best place to check imo would be a local fish shop. Oftentimes they can order a tank for you and you can avoid the shipping costs.
Other than that, ordering from a manufacturer and having a new 180 or similarly sized tank shipped to your home will probably cost around $2k, glass or acrylic.
As others have pointed out, used tanks come much cheaper, but it's often a waiting game to find a decent tank in your area and you may never get what you're looking for exactly. Plus it's used, quality can be questionable.
I prefer the DIY route these days. I can order all of the 1/2" glass, silicone, and trim I need for a 180 for around $750. But I have a bit of experience building and all the tools to do so which are added expenses...might not want to start building with something that size.
Anyways, good luck. Let us know what you come up with.