John, lower ball joints are part of lower control arms and they are one piece. 2001 models have a bit different setup, different mounts on lower control arms and detachable ball joints. $1500 for L & R is way too expensive. The one you mentioned in pontiworld.com is only ball joint and wont fit your car. You need the whole control arm which is $225 on that website. Goto
www.rockauto.com and look under Mercury Cougar 2000, 2.5L, Suspension you will find cheapest around $48 each. I have been dealing with them for over a year now and their support, warranty is excellent. There are two types. You need the one which looks like the one in the image below.
You better cross check with the one on you car. Mine is Eibach and I have the similar one in the above image.
$2000 for air con and that if you find one is again hopeless. A/C compressor can be taken out and fitted back in under 30mins. Its very simple on Cougars. R&R should cost under $50 if part is supplied by you. The compressor listed on pontiworld wont suit Australian Cougars. Its for American Cougars. You can distinguish them by the hose mounting points. It is sort of very hard to find compressors that suit Australian Cougars. You need to search on UK ebay or UK websites or wreckers. Wreckers is the best option. I had lot of dramas for over a year with air con in my car and finally fixed it by replacing a hose bought from wreckers. In this process I happened to buy a second hand compressor too from wreckers. As these compressors are rare pieces I wouldn't want to sell it, keep it for myself, will be useful someday for my car. If you have no luck finding one, then let me know I will help.
Keep us posted before you buy anything, because you might end up buying parts which suit American Cougars and not yours. Also, we will help you save $$$.
Yogi