Speaking from personal experience. I have built cabs before. Always 4x12's though. It is a very simple thing to do...IF you have good tools. My first cabinet I built out of MDF (medium density fiberboard). Turned out pretty good, it was 3/4" made solid, internal bracing etc. BUT....about 4 months after I built it, it accidentally fell off the back of a truck onto my driveway. Needless to say the fiber board cracked. I took the same speakers out of this cabinet and made a 2nd one. I made this one out of 3/4" plywood and doubled its thickness. Although the cabinet is very heavy, its a tank. Closed back non ported. I do not beleive you absoulutly have to port the cabinet. In recent years I have made side money from building car/home speaker cabinets. I do not port them either unless asked. Porting them makes them seem "boomy" to me. Unported enclosures have a tighter sound to me. Guitar or music cabinets. I have used Celestions/Pyle/Eminence prodominetly over the years. If you build the cabine yourself. Make SURE of your measurements before cutting, use woodscrews and glue to put together. Bare minimum you will need a circular saw, jig-jaw and electric screw gun. I have access to a full blown woodshop so I use table saws, jointers, routers etc. Also figure out what kind of covering to use on the finished cabinet. I had a local metal fabrication shop make a metal grill for the cabinets I built in the past. My next project will have a plexi-glass front on the cabinet with neon light inside so you can see the speakers etc. ....yeah i know, I got too much time on my hands!!!.....

EDIT: Depending on what your budget is for materials. Decent 3/4" plywood is not that expensive. Just use regular plywood, not cabinet grade.