I have done some testings on spells specifically requiring candles of specific colours. I understand that not every one has the resources to get candles or the availability to get candles of certain colours. I fall under this category my self. Candles are very limited around where I live (and personally I just don't like buying candles online nor making candles which never seems to give the desired effects I seek). So this may be of some use to any one else in a similar situation fretting about not having the right candles for their spells.
I'm splitting this into three categories. So bear with me.
1.) Candle Colours. Many spells require candles of specific colours. Being that I have limited resources I have asked a close friend of mine who has good resources to help me with this category as well as the following two, this was to verify that I was not the only one who gets the same results. The purpose of this category is to get results as to what happens when a spell requiting blue candles (for example) is performed as should be done and then again but with red colours to compare the results, thus determing the effect that the colour of candles has on spells. When performed with blue candles the spell works as should be. When the candles were exchanged with red coloured candles and then the spell was done, the results were equally the same as with the proper candle.
2.) Candle Presence. This category is as the title depicts - determining the results of a spell performed with candles compared to being performed without the required candles, both of which also compared to the results of the spell done with a visualized presence of the candles. Now because of the results of the first category specific colours were not a factor; and therefore, will not be mentioned. With candles the spells were complete successes. But for some reason (a completely different topic to cover) when the spell was only an incantation with no candles present, the spell failed to work. Or at least if it did it went unnoticed. For the most part results with me and my friend were the same. But in this situation the results were different, but possitive; acandle spell with no physical candle but instead the candles are visualized. For me, the results were much better and noticed quicker than when done with the candles. For my friend the results were (about) the same as with candles.
3: Wax Heaters. This category replaces candles entirely with electrical wax heaters that use light bulbs as the source of heat. By now you know how the results of candles are. Well what happens when you take away the flame and replace it with a light bulb? You get the same results. The wax used in wax burners can be used just like a candle if a wick is place in/through) it. There may be no flame but there is still heat from the light bulb. It may not give the same heat and vibration as fire energy would, but it is close enough. The spells still is worked even when performed with a wax heaters replacing candles.
To summarize all of this. When doing spells, colours of candles doesn't necessarily hold a factor. Even if you don't have candles you can still visualize the candle being there, being used as it would be used were it physically present. It's an option but you could even use electronic wax burners in place of an actual lit candle.