Inland Orange County is different than coastal--so would help to know what you've got.

I'd recommend talking to Roger's Gardens in Corona del Mar, they are very much into drought-tolerant landscaping projects and commercial drip-irrigaiton systems, and there's a guy at Roger's Gardens, very knowledgeable in CA natives. They do very professional work. I would say they tend to overplant their projects a bit, but perhaps that is because most of their customers want "instant lush".

Plants to consider, all low-water needs and tough.
Ceanothus--deep deep green foliage, blue flowers in spring
Lemonade Berry, Rhus integrifolia
Toyon-- Heteromeles arbutifolia
Deer Grass -- Muhlenbergia rigens
Arctostaphylos -- many fine species and selections, from groundcover to shrub to small trees

Aloes--many species and cultivars with spectacular flowers that attract hummingbirds
Agave attenuata -- no-spine agave with elegant archtectural form.

Keep in mind your irrigation will likely need updating and whoever maintains your property will need some re-education about not buzzing native and drought tolerant-plants into cubes and meatball shapes.

Look at the long term cost rather than the inital cost of a plant.

For example, a tree that costs $20 but needs yearly pruning at a cost of $300 per year and lots of water all its life at a cost of $100 per year.

Compare that to a tree that costs $200 but needs pruning once every decade to remove small amounts of dead wood at a cost of $200, and only enough water the first year to establish itself at a cost of $100 for that first year.

Over 10 years the first tree costs $4,020 and the second costs $500.

Which is the most expensive tree?

Am I correct in making the assumption that you are referring to an HOA's common areas? I'm not going to bother trotting out a resume, but will try to help by giving you a few points to consider.

The cost of the plants is a minor portion of the expense of a landscape renovation. The budget bulk is going to go to labor, materials to convert the irrigation system, the landscape maintenance the installers will be in charge of during the plant replacement period, etc. If you plan to install in-house from a designer's plan, are the persons responsible for that task sufficiently knowledgeable in all of the necessary skill areas?

Who is currently contracted for your landscape maintenance? If they are a full service company, they might be the best source for installation and irrigation conversion. But check thoroughly--a verbal "Oh, yeah. We can do that." is not sufficient. Also learn if the maintenance company will be able to properly care for the drought resistant plants.

What is the current style of landscape and maintenance? Drought resistant landscapes are better maintained using selective pruning techniques rather than the common practice of taking hedgers and shaping everything into balls and squares, for example. Actually all non-formal landscapes are best selectively pruned, IMO, but that is a different thread. ;)

It really is impossible to judge the suitability of plants without knowing, at minimum, where you are located. Even then, an on-site evaluation is really necessary to put together a working design. There may be portions of the landscape that would be suitable for xeriscaping, without compromising the overall lush look.

What is behind your association's interest in the renovation? Is it time for a plant renovation and you decided to check into converting lawn areas to reduce water requirements? Water bill sticker shock? The why is important, especially because of your budget concerns. If a full renovation is beyond your financial scope, there may be other ways to evaluate and reduce expenses (drip and micro-spray irrigation, different horticultural practices, etc.). Or the renovation can be done in phases.

My husband would be my source for suitable companies that would be interested and available should you want to progress to a project consultation or bids. It does not sound as if you are at that point yet. An idea of the scope and budget would be necessary starting details.

Have the association buy the Bob Perry book and pick only L/VL plants and force the maintenance crew to learn how to calculate the monthly water requirements for your ET0.

Here is a link that might be useful: Landscape Plants for California Gardens

You can do "strict xeriscaping" with with manzanitas and Ceanothus, both of which are evergreen. (Though you'll have to water for the first year, to get them established.) The prostrate forms can be used in place of a lawn.

Las Pilitas Nursery in Escondido specializes in drought-tolerant natives. Their website is also extremely informative.

http://www.laspilitas.com/easy/easy.html

http://www.laspilitas.com/groups/native-plants.html

Joining the information the GW forum members provided on this topic.

Here is a link that might be useful: Background Planting for OP