Those two photos were taken with a D-70 and stock lens. I used a SB17 sync cord to an SB-80 flash set on manual bounced into an unbrella mounted on a stand.
I was going to do portraits at one time but its hard to make any money at it for the amount of energy I would have to put into it. Action and aviation I enjoy, portraits not to much unless I'm clowning around like the above photos.
I bought two flash stands with unbrellas for $50ea. I use a cheap slave for the second flash when I use it. I also bought a backdrop stand for $100 including carry bag. The backdrop I broke the bank on and spent about $300 :? What the heck was I thinking. I have used it alot but I don't like the typical backdrop portrait photos. The last year or so I just use the one flash and crop tight like the above photos. Keep it simple is my motto.
I also have a flash meter but since going digital I don't even use that. All I do is test shots until I get the lighting I like and then shoot.
It can be done cheap but if you want to do it professionally get the right gear and learn how to use it. Don't look like you are experimenting or unsure on a paid shoot.
Eric