We just did the blood. We didn't know about the tissue until afterwards (and I forgot again, until now!). It's stored in the NJ lab (I thought it was sent to Paramus, but I see the Alphacord site now says it's in Allendale, which is quite close). We lived in New York when my son was born, and are in New Jersey now, so we'll likely use the same place for our second.
I'm not sure about the reason for the difference in costs, other than that some seem to do different screenings than others (see here: http://www.alphacord.com/compare_labs.htm), some have backup generator power while others don't, hours of operation vary (for taking out blood), and real-estate prices vary from place to place. It certainly makes sense to choose the lab closest to you, in case you critically need it for any reason.
If you do decide to go with Alphacord, I'd appreciate your kindness in using me as a referral -- I can give you whatever information is required privately.