If funds are limited, they are limited. Try it with the old manual one for now.
If it does not work you can get the DA55-300 at a later stage; the total will be more expensive, but you get a lens that is considered better than the DA50-200
You might also find that you don't have a real need for that tele in which case you have saved yourself some money.
PS
You will find that the camera will ask you for a focal length when you switch it on with that old lens; this is for shake reduction. As this is a zoom and you can only enter one value I would switch SR off (but I don't have a manual zoom); there are some discussions going on which value is the correct one so search this forum.