I do not know about the rightness or wrongness of using used candle wax for making new candles, I have done it and had not repurcussions as a result. I simply use distilled water and white sage to cleanse the 'used' candle that I may use it for new candles. Healer is correct initial cost can be prohibitive, however, being a single mom and poor I do this so that I may have my needs met without 'breaking my bank.'
If you are okay with the cleansing of old to make new then I suggest this.
The dye from the old candle with dye the new wax, use white wax as it will keep your color more true. If you color mixing then mix away, otherwise keep to white. The 'old' wax will obviously be a paler version once melted with the white wax. A cooking thermometer is recommened, so that you do not get the wax TOO hot and burn it. You can pick one up for about $5 or ask a family member who cooks if they have a spare one.
You will need to purchase wick, which can be done at many craft stores, like Hobby Lobyy, Micheals, etc... Be aware of the wick size that you purchase. As a general rule, the thicker the wick, the larger the candle it needs to go in, as the thickness determines how hot it will burn and the speed of which it will burn. Google it, you will find info on the standard sizes and their application. Wick is not terribly expensive.
You can dip your own candles, that is not difficult, you simply have to have a longer wick to start so that you have something to "hold" onto. I will be happy to give that process to anyone who is really interested, just email me.
Molds can be made out of various materials. You can make them out of scrap wood, just make sure if you to that that they are made with precision, so that your wax does not come running out of the sides. I can help with that too if you want to email me.
Plasitic can be a wonderfully economic way to make candle molds as well, you can cut up old bottles, containers to the height you need and put a wick in, hold the wick or use a metal base to run it through that sits on the bottom. The metal is not mandatory though. You can simply seat the wick in the bottom, hold in place and pour your wax in, and adjust your wick to stay in the center until it hardens just enough that you can let it go.
Metal molds can be made as well. You can also, if you have the money, invest in some premade molds.
You can infuse your candles with essences as well, which is not very difficult either.
Just realize that there are different grades of wax, the less expensive the wax, the faster your candle will burn.
If you have the time to invest candle-making can be a wonderful experience and allow you to get creative as well. If not, you may just want to stick to buying them.
Anyhow, I could go on with this for a long time, but I will stop here. Please email me if you like and I will give you what info I need.