Of course Jessica Alba can afford two corsets. A custom-made corset starts out around $300-$350 and goes on up to $50,000 BLONDS stage corset which you could never sleep in because they are encrusted with jewels.
http://www.youtube.com/watch?v=ROlfGCm_je8
$1,000,000 of Blonds Corsets
However, if you are a Clever Girl, a Good Girl, you could make something...
http://butterick.mccall.com/b5797-products-22969.php?page_id=369&search_control=display&list=search
BUTTERICK SEWING PATTERNS B5797 Printable Pattern Available
Misses' Corset, Sash and Shrug is currently on sale for $2.88 (plus shipping) and comes on sale every couple of months. If you live in one of 600 locations that has a HANCOCK'S FABRICS store you get a shot at Butterick patterns every couple of months as low as $1 or $2.
What makes this pattern special is it is a ZIP-FRONT rather than a lace-up-back model.
I found I had to make one with throwaway fabric to get my actual size adjustments -- I ended up adding a couple of inches of length for my longer torso.
Be sure to use all notches on the pattern pieces because otherwise it can get confusing with 6-left side and 6-right side mirror image pieces.
Wearing two longline bras can be effective for getting into that BIKINI BODY shape that you crave.
REMEMBER: Regulation waist size is 10 inches smaller waist than hips or bust measurements, and bust measurement is the BANDSIZE below the protuberances of the boobs which add an inch for each cup size.
You could buy an All-in-one body-shaper, but actually you need a few of them if you don't want to be hand washing them every night and then sleeping in a wet garment. At $80 a piece you will be getting set back $500 to $600 for a week's supply, and that's just wearing one at a time, not two at once. Again, if you look, you will see that bathing suits and body shapers share a lot of the same attributes.
http://butterick.mccall.com/b5795-products-22967.php?page_id=4422&search_control=display&list=search
This is a Butterick Pattern for a plus sized (QUEEN SIZE) swimsuit...
This pattern is rather complicated and I would not recommend it for beginner sewists. But it conveys the idea of the similarities between swimsuits and body shapers. You might be able to find the following book from your local library...
It's time for all Good Girls to be getting into shape and working on that regulation waist size and your BIKINI BODY.