G'day Norm
Buy an OIII filter, they work brilliantly with 250mm Dobs. Then if you are sufficiently motivated and have saved up a few dollars buy one fantastic eyepiece something like a Nagler or a panoptic. Remember a top eyepiece is for ever no matter what 'scope you own. Personally I dont rate barlows for one simple reason, extra glass in the light path. also I personally find they are a bit of a stuff around but hey, Im lazy.
Oh by the way I realize some eyepieces particually long eye relief models have barlow elements.
