only started 3 days ago, but for giving DS one supplemental evening bottle, I've found manual expressing fine - cheap pump, and very easy to use. i've got the tommee tippee pump. i have not tried an electric pump though!
if you're 38 weeks, you hopefully won't need to worry about expressing for a while though - think the advice is to wait until breastfeeding is well established (4-6 weeks) before introducing a bottle.
I just expressed for 6 months with DS1 using a handpump and at the end of that time I did feel like I had RSI. I tried an electric pump at the hospital over 3 years ago and found a hand pump to be more effective at that time. However I have just hired an Ameda Lactaline to express for DS2 and would recommend it. You could try hiring one and see what you think before buying. You get sterile packs for the bits that come in contact with your breasts/milk so safe to hire. My only word of caution is that when I switched from handpump to electric I was so amazed by how much easier it was and how much I was getting that I think I overpumped and got two bouts of mastitis from engorgement or bruised boobs.
I tried a handpump (tt) early days but found it unpleasant to use and didn't get a lot out. When DD was 6 months (can't believe I waited so long!) I tried hand expression and found it to be fantastic! Plus no parts to wash/sterilise etc... Bit like milking a cow but very effective. I can easily get 5 oz out in a day if I take an oz off after a feed.
Started a thread a while ago and ladies said that hand expression is actually just as good as an electric pump - only diff is a pump might be a bit quicker.
Good luck - 38 wks isn't too late to be thinking about it - as I say it took me until dd was 6 ms to really get into expressing. Some women never get their heads around it/do it.
I have rather small breasts and found expressing quite difficult. WIth a medela double pump, I was able to do it quickly and comfortably. Don't get the Avent ISIS pump. It hurts and it very machine-like!
If you think you'll be doing alot of it (?!) the electric pumps are really good - I think you can hire hospital grade Medela ones which are MUCH better than the smaller ones you can buy. Having said that, when I was only occasionally expressing, the manual pump was fine. Your hand will hurt after a while though!