Altering sleeves/neckline on a lace dress....

While a gorgeous dress, you can definitely find a similar one without a high neckline or bell sleeves without having to pay for the cost of major alterations.

The neckline is one full pattern of lace, you can't just cut it off to reduce the neckline, it would cause a massive amount of awkward lace asymmetry. A good seamstress would probably want to rework the whole thing which would be very expensive (probably a couple hundred dollars at least). You would have to buy extra lace, extra english net, and pay for the labor ( $$$ )

ETA: The sleeves probably wouldn't be a big deal if there's enough material near the wrist. I would be more worried about the neckline.

I agree. My dress was custom made with lace and when we discussed the neckline, the dressmaker had to do it in a way to follow the lace pattern, otherwise you lose the look of that particular lace. I think the sleeves would be an easy alteration, but not the neckline.