I'd say 2-3$ at your skill level.

I agree with an above commenter, DON'T under-price yourself please for the love of all that is holy!  
100 points = $1 (when using the commission widget, pretty sure)
So when people suggest you sell your art for 50 points...that's 50 cents!! x-x
You should charge at least $5/500 points for your artwork, in my opinion. Your art is cute, clean and you're good at drawing outfits! If you did more shading, more details and did backgrounds to your drawings too, you could charge even more! Let's push for decent prices. I've worked so hard to improve my art skills and I'm still trying! I just put my foot down and decided not to sell my character portraits/busts for under $40 anymore.
Guess what.....I just got a commission! Just bought myself two Victoria's Secret bras with it too! It feels amazing to be paid decent money. 

Also, a tip for when advertising your commissions - a good place to advertise yourself is to search for "looking to commission" in the search box (under the "journals" category, make sure you select "newest" too) and comment on any journals related to what you're selling! That's what I do and it works well!  

Don't under price yourself, these are cute, simple, their poses don't change much so that will bring the price down a bit. If you want a half fair price but still have the possibility of buyers I would say 5$ or 500 points

$2.50 sounds awfully cheap, don't underprice your work and time. I would at least charge $5 per hour it takes you to create the drawing. So if it takes 2-5 hours to make one, I'd price them somewhere between $10 and $25

I think you could charge 250 or $2.50, maybe more. However, the thing you need to consider if you go with that price is that it might not sell. Since you are not a very well known artist and I haven't seen you advertise here much, it might be hard to sell at first. So, my advice would be to start low, maybe 50-100 then raise the price as you get more popular.

It depends on how much of your time is spent on it.