I might be able to help out or even host the TB change. (I'm in McKinney)
If you have a 1.8L I even have special timing belt tools to help out.
One tool locks the cam gears in place which helps when reinstalling the timing belt. I also have a tool the locks the crank when torquing the crank bolt. Finally, I have a nifty seal puller tool for removing those pesky cam and crank oil seals.
I will gladly supervise since I've done about 5 Miata Timing belts and might be conned into turning a wrench or two.
BTW, I typed up the following for a friend. Might be of some use to you too. Prices may have changed some.
The timing belt is pretty involved. Lots of labor is involved in it’s replacement. I’d recommend having a few things replaced in the process.
This list is extensive but most of it is right there when you have to disassemble everything anyway to do the timing belt. It’s preventive maintenance. I’d rather replace these common failure parts now instead of having to replace them later and pay for or redo all the labor all over again. Prices are for parts only. Most prices come from http://www.trussvillemazda.com, which has the best prices I’ve seen for Genuine Mazda parts. Labor could range from $300-$500.
60k Service
Timing belt*
Tensioner spring*
Front Crank and Cam Seals*
Valve Cover Gasket* - *Included in TB Kit $67.68
Water pump - $62.34
Radiator coolant hoses (3) - $25.74
Thermostat - $9.95
Thermostat Gasket - $1.00 est.
Bypass Hose - $6.00 est.
Radiator Cap - $11.46
CAS (Cam Angle Sensor) O-Ring - $1.00 est.
New Alternator and A/C-PS Belts - $25.00 est.
Engine Coolant and Flush - ?
Oil and Filter change - $25 est.
Spark Plugs - $5.28
Spark Plug Wires - $27.54
Fuel Filter - $26.34
Air Filter - $10.50
PCV Valve - $11.40
Mazda also recommends changing the manual transmission and rear differential gear oil.
Redline Synthetic (3 qts.) $24.00
My guess is your quote is the bare minimum in parts replacement.
Timing Belt, Spark Plugs, Air Filter and Fluids. For that, their price is about average.
I’d personally pay more to have all the above items replaced. Overkill? Maybe. An ounce of prevention is worth a pound of cure. Your call, pay now or pay more later.