perhaps you can replace the area with a small stove top and oven (24 inch wide)or slide in range and you can use the empty space in the wall for a convection microwave if you want fast cooking without bending down. It might not cost more then replacing an in wall oven especially if you have to worry about rewiring and cabinet repairs. Additionally,some of the small ovens are non electric ignition.
In the meantime if you have or can borrow a stovetop oven from someone (Camping/pesach style)it would be faster then toaster oven.They retail bet.30-40$
p.s.downside of convection microwave: most convection microwaves due to the cooking methods and mix of inner metal and plastic cannot be kashered for pesach,and should be treated like a regular oven I.E. designate it for milchigs and the main oven for flieshig and double wrap items if switching.The upside is it browns as well as an oven and cooking time is more then halved.