I've got some laying on my desk right now. They did come from Walmart; but I don't know if they still sell them or not. Originally, the barrel is in two parts. The upper half is a silver colored metal sleeve and the lower part is a rubber soft grip. Mine are blue; but I think they come in several colors. As I recall they came in 3-packs and were about $3 per pack. They take a Parker refill.
I can post a picture of one tomorrow if you want to see what they look like in original form.
There ws a thread about these pens and the conversion posted on IAP......maybe within the last year or so. Maybe I can find it for you??