If the only radio operated speedlite is the 600EX-RT,
you can only set up multiple hidden flashes by using multiple 600EX-RTs.
None of the other Canon speedlites will work as radio transmitted slaves.
I seem to have been confused by how the term wireless is used to mean Infra Red (line of sight) wireless and/or Radio Transmitted (radio) wireless.
Based on this a 600EX-RT MSRP $629.99 x 3 = $1,889.97 for a minimal radio set up of 3 flashes. Leaves a lot of room for third party flashes that are only radio transmitted.
I don't know if this helps but this is a little less expensive than the $1,890 you calculated above.
600EX-RT - $569 (Amazon & B&H)
ST-E3-RT - $306 (Amazon)
ST-E3-RT - $319 (B&H)
2 Speedlites with ST-E3-RT - $1,444
3 Speedlites - $1,707
No doubt, a lot of money, keep an eye on used (ebay, CL) and upcoming Canon rebates. Do you have a lens rental facility in your town who rents Speedlites?
Also there has been a rumored radio controlled flash for some time to replace the 430EX which will obviously be cheaper than the 600EX-RT. I was expecting to see it before then end of 2012. I think someday we will see it but I've given up on any predictions. I think Canon wants to sell more 600s first.
MSRP numbers are great for calculating set up cost. Time spent doing the searching, calculating and testing become the costs of taking photos with the best gear.
You always feel better when you go to a great source such as B&H, Adorama or Amazon and get a better price than Canon's MSRP.
I am located in Canada and I have local sources as well, including Canon.ca, B&H.ca and Amazon.ca. Pricing is historically higher here.
Learning the logistics of acquiring the best Canon gear for the best price has become a great learning experience.
My confusion over wireless IR vs. Radio wireless has led me to pick up 2 320EXs used. Sure I can use them with IR but that was not my intent. I thought that 320EX was the rumored radio controlled flash............ the compactness and LED feature may be worth it.
I will buy the 600EX-RT today. I do not see me buying a transmitter @ 60% cost of a full flash.
Thanks for your input