I'd go with a small wattage HID setup, maybe starting with a 400W metal halide setup. Being a grower of many types of plants myself , I would NOT recommend getting started with fluoros at all, because eventually you'll just upgrade and your original investment will be wasted. The key is the efficiency. HID lights generate more lumens per watt (light per electricity usage) than fluoros, so you will pay less. Depending on how serious you plan on getting , getting a dimmable ballast and using it , say , with a 600 watt bulb at 50%, may be a better place to start electricity wise if you plan on expanding later and you can afford the up front costs.
Cacti are likely going to be the only plant you can grow on a desk.. the others get too big and require too much light to fit conveniently.
A 400 Watt HID and a decent reflector will allow you to grow half a room full of cacti. You may want a 600 Watt to be safe if you plan on growing a lot of plants too.. They require more light because their top leaves shade their bottom leaves which can lead to spindly or uneven growth if they are not illuminated enough. If you ever plan on growing certain members of the cannabaceae family (obviously i would not recommend choosing the illegal species in this family), you are going to want more light. Also consider how far deep into gardening you may end up getting. It is VERY addictive. To give you an example , i started with a single 10 year old pedro under a 400W HID. 4 months later, I have accumulated an additional 400W light, ballast, and reflector, as well as a 1000W light ballast and reflector.
Another thing to consider is getting a dual bulb reflector. You will be able to add a bulb later if you need more lumens. Reflectors assembled usually cost between $80-250 retail so keep that in mind. Ballasts, between $100-$300, and the bulbs, if you want to get good grow bulbs, at least $40-60 each online, more in stores. So consider your total budget first .
As far as height, it depends on how many plants you have and what your grow area (sq feet) is looking like. With different species, you'll undoubtedly need to utilize egg crates / textbooks / cardboard boxes to put them all at the right height for their individual requirements. Higher wattage lights illuminate larger areas with more lumens. Smaller wattage lights will give you the same lumens, but only if lowered closer to the plants, reducing your useable grow area. For cacti or low light requirement plants, plan on having your finished reflector assembly hanging between 2-4 feet from the tops of your plants. For higher light requiring plants, you might want to think of going a little closer. This is with a 400W setup. For reference, however, there are cannabis growers who put their 1000Watt lights only a few feet away, so you can see that plant requirements vary dramatically.
If you start with a 600W setup with a good reflector, you should be able to put your herbaceous and woody plants underneath it directly, you will have more than enough lumens at the outside of your grow area to raise cacti effectively.
Cacti for one will give you better growth rates being closer to the light, but they must be acclimated first or they can sunburn easily under 400W or higher.
Also consider the fact that metal halide tends to promote stockier, faster stem growth. HPS simulates autumnal light conditions and tends to induce flowering easier in susceptible species, and should be used when intending to maximize yield or growth of a flowering crop. However all the plants you listed contain their active ingredients in the leafy material of the plants (or the stem in the case of succulents). Luckily MH bulbs are cheaper, but unfortunately they are less efficient and have a shorter life (1 year of 16hr operation)
When considering a ballast, consider the temperature requirements of your space. Magnetic ballasts (aka coil ballasts) will raise the temperature of a typical bedroom by about 10 degrees farenheit if the room is closed. However since you will be growing indoors mostly in the winter, you shouldnt have to worry about this. Electronic ballasts aka chip or semiconductor ballasts emit very little heat. If you can find them for a good price, i would recommend them, however, they tend to be less reliable, so find a brand with a good warranty. Lumatek makes reliable electronic ballasts. The advantages of electronic ballasts are that they draw much less power, extend bulb life, and in some cases increase lumen output. They also decrease flickering that can occur as a bulb gets old, since they run the light at a more optimum frequency. The disadvantage of electronic ballasts are that they create a large amount of RF interference. Magnetic ballasts main advantage is that given good care they will last a lifetime, and have user serviceable parts. Electronic ballasts , on the other hand, can include a dimming function, allowing you to effectively run a large watt bulb at as low as 25-50% of its normal output. Very useful for switching between different species as your needs change.
Hope this helps!
