I assume by back yard flyer, you are looking for low slow, and maybe micro stuff?
Just about all of the Airfix 144th scale single engine jets are MMX convertable.. I'm waiting for the F-104's to come in but if it is the size stated I think it's gonna be perfect for MMA 4.5" long and 2.25" wingspan
the F14 Tomcat is also MMX-able with dual motors...straight duct ejections... I ordered an F16 but will have to see it.
If your looking for regular size PMC's, they have a huge number in the sale that are curtain to spark interest, 1/48th single motor migs. F16, F8e, F4's, and tons of euro jets. Heller, AirFix, and Special hobbies have a few Space related models on sale also 144th saturn-V (Excellent 5 C cluster model or 3 D12's,) 1/48th X-15 but still a bit pricey, 32nd Bell X-1 is micromaxxable but will only get about 8' on a MM-II motor on a CALM day
Praise the .5 sec delay on that one
LOL.... most of the Russian launch vehicle, and all the Ariane series are also good buys. The list could go on and on but it's what your looking for and how badly your better 1/2, in my case better 2/3rds is going to kill you went she see's 34 New plastic models come in
HOO1 I'm gonna be in Trou-beLL LOL ducking!