NTB - is this good?

No. The cost sounds way too low. First of all, what is the $20.00 per tire for, the cost of each tire or just the labor to mount and balance them? You will not find new tires for that price so it's either the labor charge or those are used tires.

CV joint boots can be replaced separately but that can be a time-consuming and miserable job on most imports, so conscientious mechanics will typically just replace the half shaft to save you money. Rebuilt shafts are pretty inexpensive.

An alignment is not necessary just because the shaft was replaced. The mechanic will recommend that if he sees evidence of abnormal tire wear or if you complained of a pull to one side when you let go of the steering wheel or the steering wheel is off-center. Many shops will not warranty their tires unless the alignment is checked to be sure it is right. They don't rely on simply "reading" the current tire wear because they don't know how long the old tires have been on your car or whether they were just installed to hide the bad wear. They will also inspect the steering and suspension system components before they do the alignment. It's a good idea to have that done anyway every year or two; more often for Ford products.

I don't see any reason to be concerned about the cost. I doubt the shop appreciates you bringing in your own parts though. Doing that cuts their throat, so to speak, and robs them of the little profit, but more importantly, what will you do if one of the tires is defective and has a slipped belt or if it causes a tire pull? That's what the profit goes for to cover if that happens. They will have to identify the bad tire, then replace it. That's a lot of extra work they don't charge you for. Those costs are absorbed by the shop. That's what the profit goes for.

In this case, since you supplied the tires, you are responsible for any costs associated with any problems that occur. This is the same as bringing your own food to a restaurant and asking them to cook it. Some shops will refuse to install parts you supply because they want to avoid potential arguments over who pays for replacing defective new parts, (which happens quite often; the parts I mean, not the arguments). Some mechanics just get snooty because you robbed them of their profit which helps pay the expenses the business incurs. (You don't mind allowing Walmart or your barber to make a profit). Contrary to our current leader's political viewpoint, profit is not evil. It is necessary.

Some shop owners welcome you bringing your own parts because if one is defective they will have more work they can legitimately charge you for, and they don't have to go through the misery of getting it replaced. They can let you do part of their job. Then, ... Believe it or not, there are shops that will gladly install your parts because they too want to save money on their purchases and they understand you do too. They are relieved of the task of helping you select the right tires for your car. They don't have to try to justify the cost in your mind or prove you're getting a good value. They may not even stock tires and you saved them the trouble of ordering what your car needs. Many business owners look at that as you having done part of their job, so why should they grump when that saves you some money. My last boss an I would not mind installing your tires but I would not relax until I knew they weren't causing any problems.

From your descriptions it sounds like you're getting a fair price quote. If there is no problem after the work is done and you've driven about a week to be sure, I would entertain the notion to return with a bag of cookies to show your gratitude. We had customers bring us stuff at the dealership I worked at about two or three times a week. (Chocolate chip cookies or chocolate covered donuts are preferred)! Most mechanics, at least the smart ones like me, are fueled by chocolate.