I wouldn't trust my neighbours child, he's liable to throw them over the hedge about 3 doors down
I've thought about this too, but it wasn't any cheaper for me to use another courier, but then I'm in Northern Ireland and there arent exactly a lot of courier services here.
Franking is cheaper than normal, but will only save you about 8/9p a package, when you take into account these machines are expensive to buy or rent - for a franking machine suitable for up to 30 items a day (which is about the low volume one and therefore the cheapest) will set you back about £700 + Vat to buy, or about £20+ vat a month to rent.
Royal Mail will charge you about £450 a year to collect all your mail every day, 5 days a week. This works out at about 10% of your postage costs a year, so maybe you could add on the 10% to your customers, if you are paying £1.45 I'm sure the customer wouldn't notice an extra 15p. Although for that you will only get collections Monday to Friday. You can choose to hold the rest of the packages until Monday, or just nip out and post them yourself on Saturday,
Although all this information is all well and good, but it does not really answer your original question. As for do you go with another courier, I would advise you check out their websites and see what they offer.