Ckeck out the Winter Sowing forum. I'm no expert, but I would think you have time in your zone to use the wintersowing method to start some tall, fast-growing annuals from seed. And wintersowing can be *very* frugal.

If you have no kids or pets in the area, I hear castor bean plant gets big and dramatic, fast (but it's very toxic). A. manihot is a hollyhock-like annual with pretty flowers. And there are lots of tall, quick ornamental grasses. A vine on chicken wire or a homemade trellis would be another alternative.

Kristin

Just a precaution - I used to do energy audits for homeowners. We recommended keeping bushes, etc. 3 feet from a heat pump or air conditioning unit so that it gets sufficient air circulation to operate efficiently.

Here's a fancy way to screen the utilites, just to get you started thinking.
{{gwi:50554}}

With a minimum of woodworking skills and tools, I think you could use pre-fab lattice panels and stock pieces from the box store to make something nice that could blend in with the deck -- something like this:

{{gwi:50555}}

Maxygolf's right about planning a clear distance around the unit for air flow. It also makes it much easier to get in and do repairs or replace the unit when you have to.

If you're looking for a quick "living screen" to cover the lattice, consider something like hyacinth bean vine or nasturtiums. As long as you get some sun, they grow fast, cover quickly, and actually prefer poor soil, so you don't have to twaste the fertilizer.

Good luck!