I'm thinking I would really like a set of 12" liturgical action figures with full vestments. GI Joe comes with a beard now, you know, and with a small pillow tied to his middle he could also pass for a bishop. So I would like a full set of presbyter vestments in red, blue, green, gold and white; a set of bishop vestments, including mandyas, sakkos, omophorion, staff, crown and di-trikeria; and diaconal sticharia and oraria in colors matching the presbyter's. Also, for undress, we'll need some riassas, pectoral crosses, and maybe a black cape (I've always been partial to those).
Then we can get some readers and acolytes, with processional crosses, ripidia, and candles; kadilos with stands and incense boats for the deacons; a Gospel for the Little Entrance, an Apostol for the reader, and a hand cross for the presbyter.
Finally, we'll need a nice mix of people to populate the liturgy--babas and babies, moms and dads, and some teenagers. We can loot the Barbie aisle for figures, then dress them up in appropriate clothing.
To accessorize the collection, I suggest that a build-your-own iconostasis kit would be very educational, and would work well with a combination Holy Table/Proskomide kit with altar cloths; lance, chalice and diskos; aer and epitaphion.
It would cost a tidy piece of change, but you could build your own church and actually walk through the various services in miniature--which would be very useful not only for altar boys, but also for adults wanting to understand the liturgy better, and even the odd diaconal candidate or two in need of visual aids.