I know of a FANTASTIC peacock supplier who I get my fish stock from. You will get them via air cargo and I think they always use Southwest Airlines. You may find information on them if you search Facebook for <vendor name removed>, they are located in Missouri. My concern here, though, is that you will be putting very peaceful peacocks with aggressive Mbuna. As Noki stated, the Lwanda, or any peacock for that matter, will not display it's color potential while housed with more aggressive species of cichlids such as mbuna. From my experience, you either have Mbuna, or you have Peacocks. Do not mix the two. I have, however, without incident, been able to keep a yellow lab in with my peacock tank. You will want to have at least a 6 feet long tank since Peacocks love to swim side to side, and also, to afford plenty of territorial space. A long time friend of mine schooled me a while ago on the best practice for keeping beautifully color peacocks and here is what I learned.
Have a male only tank and house one of each variety of Aulonocara mixed with some of the more peaceful haps and protomelas. There some lovely color varieties of aulonacara jacobfreibergi, as well as the Stuartgranti sp. On a regular basis, <vendor name removed> gets the following and they come in at 4-5 inches. One thing to also note about the fish they get in - they are from Pablo Tepoot, the developer of NLS fish food. Here is the most recent shipment they had come in -
Flavecens
Ngara flametail
Red Jacobfreibergi
Blue Gold
Sunshine
Rubecens
Lwanda
Turqois
Mandarina (see Pablo's book volume 2 on amazon and you will see this fish)
The following are Haps/Protemales
Red Empress (beautiful)
Borleyi red fin
Lithobates Sulferhead
Azureus
Again, I wouldn't recommend these fish in with any Mbunas, well, except for a lone yellow lab. If you want some pretty fish that will swim out in the open water of the tank for you to see all the time, go with Peacocks. I myself leave Mbunas alone, got tired of my hospital tank being occupied

Best of luck! Also, I realize that this post is a bit dated but maybe you are still looking. Take care!
Jenny