Sally, Yes, I'll definitely recommend electric pump. But note that if you just pump in the morning / evening, I don't think the milk supply can sustain till six months. You need to pump / feed at least 3-4 times a day to sustain.
If you wish to continue feeding after the b-trip, you must keep pumping regularly during your b-trip, at least 3-4 times a day. Since milk can't be kept for long, you may disgard the milk pumped during your trip or drink it fresh yourself.
Newborn - 8-12 meals / day
2 months - 4-5 meals / day
Milk may be kept in refrigerator for around 48 hours and in the freezer for months (but note that milk composition will change as the bb grows), provided that temperatue remains stable. If you can't keep it in a stable environment, disgard it or, if you don't want to waste it, drink it yourself.
The cost of electric pump varies according to brand and model. Some single pumps (which is claimed to have "advanced" features) are more expensive than some double pumps. One needs to compare the features and prices.
newborn needs to be fed every 3 hours (or at most eevery 4 hours). 2 months, roughly 5-6 times per day. you are lucky if you have that much of milk surplus. in that case, you can freeze the milk for "emergency use". whenever we do not feel well, the milk production drops. that's very frightening. if you go to a full time job, your baby probably will need at least 2 feeds during your working hours. what you pump might be just enough for the feeding at home.
well, price of pump differs mainly because of quality (the company puts more $$ into research and development asks more). if under the same brand and rank, double pump is definitely more expensive than single pump.