Hi,
I teach the cello. It is not necessary to invest in a cello unless you are really committed to learning 'no matter what'.. I usually let my students use my instrument for the first couple of months...then, they decide once they're confident that they love the instrument and wants to go on with learning...
Do pm me if you've got any questions.

Always try to get someone to play the instrument for you if you can't do it before buying the instrument. You've got to hear how the instrument sounds and feel before buying one. It's always good to begin lessons before buying an instrument so that you know what you're getting into.
When buying an instrument, look out for the set up of the the instrument. Is the bridge too high and therefore, strings will be a little too high from the finger board which results in difficulty in getting the strings down to obtain a nice sound (especially for beginners). The wood of the cello is also quite important though most beginner cellos are made of ply wood. But there are some that have nice grains to it. Also, look out for the finishing of the instrument. Try to avoid the really shiny ones. They look like their dripped in heavy lacquer and this will affect the sound of the cello. Expensive cellos are shiny, only at close range. The shine/gloss/glow is just different in expensive cellos. The cheap shiny ones are just trying to look glowy and you can tell that it's so fake.
There are a lot more aspects to choosing a good instrument but if you're new to the instrument, it's best to bring someone (teacher, friend, relative) who knows something about the instrument with you when buying. The cello is quite an intimate instrument compared to the piano and so it's important to choose wisely. There are also a lot of cellos out there that are flawed. Good luck!