Hello,
IMO Dallas is a good place for quality work at reasonable prices. Last year, I read one post that was quoted $27,000 for a 3-ton system installation. I also read a post of a $2500 3-ton replacement. This is a lot of difference.

The typical price is between $3000-5000 for a 3-ton system replacement. Duct work during the summer can be very expensive. I have heard of guys charging $2000 a day to work in the attic during the summer. These are not dishonest companies, just guys that do not want to work in the attic on a 100+ degree day. If your system is in the attic, do it while it is cool. (Now) There are so many quality HVAC companies in Dallas. Quotes like yours are for people made of money. I read and heard of many 3-ton replacements last year in the $10,000 range. I can not imagine what caused the cost to be so high. A typical system can be installed in a day with 2 men. Labor and 2x markup is nowhere near $10,000.

Even in Legacy, this is a high price. I am helping someone that was hosed last year with a 5-ton installation. He now has the state of Texas involved. He was hosed so bad, that his case was placed in front of 30 previous cases waiting for proscution. The sad thing is the company that did the hose job has a fair reputation. The installation was incomplete, yet he spent $6200 for a 5-ton replacement. The company tried to charge him an additional $2k for a 1/2 days work replacing a couple of ducts. His summer bills were over $1000 a month for a 2600 sqft house.

Get multiple bids. I know of one wholesale installer that will replace a condenser for under $200 labor. (Last spring) This is very cheap for Dallas. This is less than I charged in the 1980's.

If you intend to replace all three units at one time you should talk to this company in Austin. He manufacturers a system designed for Dallas and hot climates. His equipment is like commercial equipment, and is truly efficient.

http://www.alliedenergysystems.com/thermal.html

Replacement of lines depends on the requirements of the new equipment and not age or condition of the lines. Sometimes this is needed for maximum efficient operations.

Any handy person can install new duct. The key to a good job, is to seal all joints and seal the insulation properly. Many installers use a mastic to guarantee the joints are sealed. For a very efficient duct system consider using foam spray insulation on the ducts.

Installing a system requires a few tools. Guages, Vac pump, torch for silver solder, Volt-amp meter, and a few sheetmetal tools. Basic mechanic tools also. For legal service work you need a recovery machine. By law, you need a CFC certificate to buy freon, or systems. You are also required to have it to adjust freon. Most cities require a permit to replace HVAC equipment, but less than 20% of the residential work is permitted in the Dallas area.

Now, for the good news. The state of Texas will issue you a voucher that allows you to purchase equipment for your house, if you have a cfc certificate. Kinda neat.

If you have specific questions email me. I am in N. Texas area.

I'm in the final stages of replacing my AH, HP and Lineset.

If you're handy, eager to learn, and willing to invest tons of time then go for it.

I spent well over 100 hours getting my EPA universal card, understanding refrigerant theory, practicing my brazing technique, doing dry runs of evacuation, learning sheet metal, studying schematics, etc,etc,etc. This time was invested before I even started the installation. The Pros want you to think that without a doubt HVAC is beyond DIY. I'll be the first to admit that HVAC is not a "typical" task suited for "Joe Six Pack Homeowner" but it can be done and you can save a bundle of money and end up with a better installation then the average contractor. Be prepared to face plenty of surprises along the way - they'll surface no matter how well you plan.

My motivation started out as cost savings. It quickly changed to a passion to learn HVAC and do a job that would surpass all but the best pros.

In your case I'd think twice about the lineset. Most new equipment requires larger linesets for max. efficiency. If you're going with R410 you should really change out the R22 lineset. (I went with R22)

I'd also be concerned about the ducts. If you're changing ductwork then you better be prepared to do a complete manual D and J to ensure your getting the right capacity system. There are tons of variables - don't guess.

Good luck.

P.S. I budgeted about $1k for tools, test equipment, books, pumps, misc supplies and incidentals. It's comming up real close to that.