I don't do gum paste work often....usually make all of my decorations from Satin Ice fondant.  I want to make this cakes topper with a 50/50 GP/F mix.  I was going to get Satin Ice fondant from  Amazon (5lb bucket for $23.50), which I thought was an ok deal.  I have never made my own, and this is not the cake I want to experiment with new fondants on.  Im not sure about the GP though.  For a 2 lb bucket of Satin Ice GP its $16.25.  This seems pricey to me and Im trying to keep costs low.  Should I go ahead and purchase, is there a different supplier of the same product for a better price that ships free, or can you recommend going a different route that is reliable but more cost effective.  I would appreciate some guidance here.  ...Also, I am only making a rainbow topper for the 6" top tier of a my little pony cake, so I don't really need a 2 lb bucket.  TIA!

I have always made home made gumpaste and found it to be not onl y economical but also very sturdy, holding well when humidity.

I live in the desert, so while humidity isn't an issue, I am concerned about cracking.  Would you mind sharing your recipe for GP?

I would just add some tylose to the satin ice if it just for a rainbow. I find the satin ice gumpaste takes too long to dry anyway.  Making your own is pretty easy and works well. 

I use one egg white, and gradually beat in icing sugar spoon by spoon until the mix is stiff enough to be dry to the touch. pop a couple of rounded teaspoons of tylose powder in , rub a teaspoon of solid vegetable fat  ( crisco or something like it ) onto your hands and work the paste until it is nice and smooth , Smear a bit more of the fat around the outside , wrap in cling film, a freezer bag and then a ziplock . Pop it in the fridge over night and it is good to go. I portion it up and freeze it til I need it.  But I make a four eggwhite quantity at one time. 

Awesome! Thanks for the help :)

This is  a link to Edna de la Cruz' recipe, she says soft peak stage and shiny then add tylose.

I always use Nick Lodge recipe. Here is the recipe. I generally use 1 1/2 lbs of sugar so the paste is not so hard to work with. If you use the full amount and its too hard to work then you can add a little extra egg white. It's very messy that way. That's why I start with less and if its too soft when ready to use I add extra sugar half cup at a time. 

Tylose Gumpaste
Tylose is an alternative product to use in making gumpaste instead of gum tragacanth. The advantage of the Tylose is that the paste is less expensive,, easier to make, holds up better in humidity and is whiter in color. The 55g container makes approximately 3 pounds of finished gumpaste.

The following recipe will make approximately 2 pounds of gumpaste.

4 - Large Egg Whites
1 - 2 lb. bag 10x powdered sugar 
12 - Level teaspoons Tylose (Available in our online store)
4 - Teaspoons shortening (Crisco)

1. Place the egg whites in a Kitchen Aid mixer bowl fitted with the flat paddle.

2. Turn the mixer on high speed for 10 seconds to break up the egg whites.

3. Reserve 1 cup of the powdered sugar and set aside.

4. Turn the mixer to the lowest speed and slowly add the remaining sugar. This will make a soft consistency royal icing.

5. Turn up the speed to setting 3 or 4 for about 2 minutes. During this time measure off the tylose into a small container.

6. Make sure the mixture is at the soft peak stage. It should look shiny, like meringue and the peaks fall over. (If coloring the entire batch, add the paste color at this stage, making it a shade darker than the desired color.)

7. Turn the mixer to the slow setting and sprinkle the Tylose in over a five second time period. Next, turn the speed up to the high setting for a few seconds. (This will thicken the mixture.

8. Scrape the mixture out of the bowl onto a work surface that has been sprinkled with some of the reserved 1 cup of 
powdered sugar. Place the shortening on your hands and knead the paste, adding enough of the reserved powdered sugar to form a soft but not sticky dough. You can check by pinching with your fingers and they should come away clean. Place the finished paste in a zip-top bag, then place the bagged paste in a second bag and seal well.

9. Place in the refrigerator for 24 hours if possible before using to mature the paste.

10. Before use, remove from refrigerator and allow the paste to come to room temperature. Take a small amount of shortening on the end of your finger and knead this into the paste. If you are coloring the paste, add the paste color at this stage.

11. Always store the paste in the zip-top bags and return to the refrigerator when you are not using the paste. Will keep under refrigeration for approximately 6 months. You can keep the paste longer by freezing. Be sure to use zip-top freezer bags. If you will be freezing a batch of paste, allow it to mature for 24 hours in the refrigerator first before placing into the freezer.

Thanks for all of the detail SweetTooth!  That is really helpful.  I am going to follow this one.  

The above makes a lot, I suggest you make half or even quarter the recipe and see how it goes.