At our shop, we often put Larsen fractional size cello strings on students' instruments who are looking for that extra bit of power and articulation out of their smaller instrument. They are reasonably priced, and offer a nice upgrade for a budding young cellist!
from the manufacturer:
Larsen Fractional Cello: Keeping all things in proportion: Our aim was to offer Larsen cello for smaller instruments without compromising the Original Larsen sound. Our fractionals are purpose designed, perfectly proportioned versions of our full size Originals. The same high grade steel cores wound for A and D in stainless steel flat wire, while G and C are based on a concentric multi-stranded steel core wound with high grade tungsten.