Ioptron skyguider or skytracker

[nmoore6]

Hi all. 

I'm trying to get into astrophotography in the cheapest way possible. I have a Nikon d3300, a vanguard tripod that I believe can handle up to 13lbs, and a sigma 150-500mm lens. I'd like to try my hand at long exposure shots on dso's without spending all kinds on money on a new mount. I've seen these skytracker devices from ioptron and was wondering if I would get good data with these. I have a feeling my lens might be the bottleneck, if so, any ideas for a good affordable DSO lens (under 300 bucks)? Any help on info on the guider or better lends would be appreciated!