@Kialmur – any time you approach purchasing at a very small scale you are going to pay more, and often a lot more, than if you purchased in bulk. So if all you're looking to buy is small amounts it's going to be expensive. Unfortunately, I don't think there is going to be a good answer at the scale you're talking about.
Making chocolate from nibs is different than starting from beans and learning to roast is an integral part of many makers’ journeys – so I definitely recommend starting from beans, even if you start out roasting in a convection oven. I've taught many classes using residential convection ovens. You can also roast nibs if you find the roast too light.
That said, there is value in starting from nibs before moving up to beans as you can become comfortable with many of the processes before you introduce all of the variables associated with roasting. I recommend starting out with five-ingredient (nibs, sugar, butter, lecithin, and vanilla) to understand what it takes to make a classic chocolate recipe you like. Then you can take out one ingredient at a time to understand what they do in a recipe. You may be committed to making two-ingredient chocolate (mass, sugar) but even so I recommend starting out with more classic approaches and simplifying recipes only after you gain experience – in the long run not being dogmatic about ingredients will make you a better chocolate maker as you can come to decisions based on your experience and what you like to eat and make. I personally always advocate adding enough cocoa butter to make your life easy. I also like to grind in small amounts of salt into the recipe because salt reduces bitterness and enhances flavor (I emphasize small amounts).
Also, there are no strict rules. You can treat sugar and milk powder as inclusions. Not only do they change the texture of the chocolate they also change the perception of sweetness and milky-ness as the crystals/particles are not coated in fat and therefore dissolve in saliva much faster. In other words, do not hesitate to experiment. When you can, start with cheaper origins (and do not be afraid of Ghana) so you're not afraid to ruin them. I know Guittard in the US sells 20kg boxes of nibs and I am confident you can get them in Canada so that's a start.