I like this board and know there are people out there more knowledgable than me on this subject. Help me out, please.
I am looking at building a house. I cannot find what I really want in the school district (all the while prices are rising) I want so building may be my only option. To try to keep the price down I am using a stock plan that this particular builder uses. It is here.
http://www.woodlandhomes.com/home-designs/charleston-b/new/charleston-b-page.html#
It is a fairly nice neighborhood with homes in the $300-450k range. I am attempting to squeeze into the bottom of the neighborhood near the 300k range with maybe a small chance of expanding later. Yeah, I know it sounds cheap to all you California guys, but I live in Alabama and don't make six figures. I also support a wife, 4 kids (plus one on the way), 2 Porsches, a Miata, full size pickup, Suburban, and a few hobbies in my spare time.
I will probably add a 5th bedroom option upstairs with a Jack and Jill bath. I want a nice house, but cannot afford to be extravagent. It's going to be tight already, and the Porsche doesn't need to be put any further down the queue than she already is, if you get me.

I want as much bang for the buck as I can get. I am looking especially for things that increase usefulness or utility or even appraisal value without adding a lot of extra cost. Tell me your ideas and what you did. Has it worked out well? What would you do different next time?
I am trying to think of gotchas and know there are a ton of them. I need to eliminate as many as possible ahead of time. Here are some of the things I am thinking. The prices are from the builder's architect.
1.Get approval in writing for a garage workshop behind the house before I ever commit to build. Include size, style, height, and placement on the lot.
2. 3 car garage option adds only $8750 to price.
3. Pay for wiring and ductwork to be run around the edges above the garage, leaving an empty flat storage area above the garage. $300--500 I could possibly heat and cool this as another room at some point in the future, but just storage for now.
4. Extra 1/2 ton in size of A/C unit for the upstairs in case I decide to heat and cool my storage area later.
5. Attempt to get a 26' or 28' deep 3 car garage instead of a 24' deep one. Not sure if it is possible since it may affect the roofline too much.
6. Garage ceiling joist reinforcement in case I decide to store heavy stuff up there.
7. Maybe a higher ceiling on the end bay in case I want to install a lift and cannot build an extra workshop.

Would entail upfront concrete requirements changes.) I'd have to decide now before it is built.
8. Extra garage outlets with lights on a couple of seperate circuits.
9. 220V 50A outlet or possibly a 220V 50A and a 220V 30-40A outlets for my compressor and/or welder.
10. Extra 110 30 or 40A outlet for an RV (in-laws). Can I include both of these heavy duty outlets with only a 200 amp main breaker panel?
11. Cat 5 throughout if it's not too expensive.
12. Family room and upstairs bonus room wired with speaker cable for surround sound.
13. Should I run power, water, and sewer to the backyard garage site and cap it all off somehow so the garage is cheaper when I get ready to do that? Is there a good way to do that and meet code?(probably a local question only for code).
What else should I consider? Please lend me your experiences.
Thanks,