What you have is some one selling psudo bonsais. Bougainvillea will make an excelent bonsai, you just need the right soil and a few more things.

Here is what you do. Plant it in sandy/rocky soil with little water retaining abilitys, 'typical' bonsai soil (what ever that is!?). Then you put it in a spot where it will get direct sun for about 1-3 hours and indirect for the rest of the day. Water after the soil drys out all the way. You can keep a chopstick in the soil. If you pull out the stick and its not damp, water the plant and put the stick back.
After you start to see new growth, start to move the plant so it will get more and more direct sun. After about 1 week it should be getting direct sun for most of the day.
A few things to watch for. You do not want the soil to dry out all the way AND then get hot, so you might want to cover the pot with something to block the heat and direct sun to the pot. You dont want to cook the roots. You can use chunks of bricks or pieces of ply wood, what ever will float your boat. You also do not want to over water this plant. It likes a fast draining soil and can handle drout well.
If you do the above you should be able to save the plant.

I would agree with you that the plant is in shock right now and this is why its losing its brachts and flowers.

Where in zone 9 are you?
-Bill (zone 9-10 in FL)

I am in Sun City, CA 92586

Throw away the moss! It will compete for water with the tree, or else hold too much and rot the tree, and bougies like to dry out some between waterings, and they also like lots of sun.

I believe you are basically suggesting that I repot it. My plan is as follows: I will use putty knife to loosen soil and sort of slowly pry it out. Container has holes in bottom. I am going to cut a piece of screen door material to fit in bottom and cover with one layer of small stones for drainage. I have a set of dental picks which I use for printed circuit boards and I was going to remove dirt from between roots of bonzai and put some sandy soil in bottom prior to seating bonzai. Pls feel free to give a newbie advice on this method :-) :-)

I should have done more research before posting but I see now I should leave rootball alone when I repot. I read a lot of your posts Lucy :-), unfortunately it was AFTER I posted :-)

Uh.. thanks, but when you repot (unless you're JUST exchanging pots, which is called slip potting) you do change out all the soil (in the rootball as well) or there wouldn't be much point after all. Bill knows his stuff - listen to him too!

I removed top layer of moss and underneath is soil mixed with some white pieces. I am still trying to upload pics to my website and create link (is there a better way?). roots are growing thru soil which supports Lucy's view of moss taking water. Have lots of new bracht growing thru center of old. Several brachts have holes in them--any ideas?? After you see pics please give opinion of repot, slip pot or leave alone. Really do appreciate all of your help to a newbie "-)

My pictures are here. Select bonsai pics from my website

Here is a link that might be useful: Jesse Website

Hi, it looks pretty good! I don't think you need to repot if you can just allow a fair amount of the soil to dry between waterings, but next time you do repot get rid of half the 'soil' and replace it with something like chicken grit (from a farm 'Feed' store) or small aquarium gravel, more perlite, generally help it to drain a lot faster and then if you water 'by mistake' once too often, it won't react badly. There seems to be enough root for it at the moment.