Rick ... You are getting advice from many here that is great.
Having been an insurance fraud investigator for many years I will advise you to spend as much money, time, and effort as it takes you to install the best that you can afford. In the long run you will come out way ahead of the game as far as your long term health is concerned.
Minute particulate matter, fine dust, is easily drawn deep into our lungs as we breath. With each breath in a dusty room we are creating small fungus growing factories in our lungs and nasal cavities. Our bodies can handle some levels of dust inhalation, but prolonged exposure of this material is dangerous, shortens our lives, and can be quite deadly to many.
Especially dangerous, and often times extremely aggravating to our bodies, is the breathing in of spalted wood dust. This is, in the case of wet wood, a living organism that can easily propagate itself in the warm, moist, and very comfortable tissues of our lungs, throats, etc.
Have you ever stood in the back of a darkened room with a stream of sunlight entering through a hole in the roof? Have you noticed the stream of light in the air. This is the type of dust exposure that will get you over a period of time. It is nearly impossible to completely eliminate the small, small dust ... but anything is far better than doing nothing.
Work in a dusty area for a few minutes and then stop and blow your nose. Gross to many, but looking at the material in your tissue and seeing for yourself is the dust that I am in reference to here.
Medical bills will often be in the ten's of thousand's of dollars if we do not take some necessary precautions to catch what we can. And recovery is not guaranteed at all.
If you can only afford a shop vacuum for now, then I also recommend the use of the Rigid Shop Vac ($200+) adding the HEPA filter ($30), or a sheetrock filter ($ ?) for additional attempts of protection). But plan on additional filtration improvements in the very near future if you intend to continue enjoying your wood turning adventures.
In the spring, a window fan blowing out one end of the shop and an open window at the other (if possible) for fresh air is a good way to clear the air ... but, if you are using A/C, well, there goes the cool air and $$$ out the window.
Also, read about making the Thien Baffle filter and put this type of lid on top of a pre-separator can. It is quite simple to make and will help a great deal in keeping your Rigid clean. Be sure to check in the Discussion Center at the bottom of the article for additional users input and questions.
Go here for the simple design:
http://www.cgallery.com/jpthien/cy.htm
Also, for additional information on Cyclone Filtration go here and read all you might ever want to read about dust collection. It is quite an educational reading:
http://billpentz.com//woodworking/cyclone/index.cfm
Best of luck and always have a safe and great time finding the treasures held within the woods of the world! It is indeed an amazing adventure!