#3 Proposing to your bridesmaids
Obviously if you're just going to ask them straight-out, the cost here will be minimal. However, if you want to 'propose' using one of these gorgeous ideas, you'll most likely end up spending. (Alternatively, you could DIY your own 'proposal' for next-to-nothing!)
#4 Stamps for your invites
Who knew? Postage is very much not your friend - forking out on First Class stamps for 100 invites and 100 RSVPs will probably make you die a little bit inside. Either suck it up or look at other options; for example, create an email address for your guests to RSVP to rather than asking them to post back their responses.
#5 Alterations for your dress
Of course, it's more than worth paying more to get a better quality of service and a finish you're happy with. Set aside an amount of money in advance and find out if the boutique where you buy your gown offers any sort of complimentary alterations service.
#6 Gifts for the bridal party
These are easy to over-look - and the closer you leave it to your wedding day, the more likely you are to panic-buy and over-spend.
#7 Your band's equipment
Depending on the size of your venue, your band might need to hire extra equipment. Make sure you check what their policy on this is before you book - otherwise, you might find yourself listening to a rather, er, bitter-sweet symphony.
Also, on the subject of sound: if you're tying the knot outdoors, you might have to pay for sound equipment in order to make your vows audible.
#8 The three C's: cake-cutting and corkage
Opting for an external cake-maker and drinks provider can bump up the cost of your wedding reception significantly, with most venues charging fees for both corkage and cake-cutting. Check the small print with this one - you don't want a nasty surprise!
#9 Travel expenses
If you're travelling to your venue from a distance, you'll need to factor in petrol, train fares or even flight costs. Plus, if you're staying over the night before, don't forget to include this in your calculations, too.
#10 Catering for your suppliers
They're going to be working hard to bring your dream wedding to life - so the very least you can do is give them the option to eat! Check with them in advance - some suppliers might leave but others - such as your photographer and band - will probably be grateful for a plate of food.
#11 Lazy RSVPers
Ugh - we all know that person who, despite no end of chasing, will refrain from giving you their RSVP at the very last minute. On the other end of the spectrum, don't forget those guests who might cancel their attendance at the last moment, leaving you with an empty seat you still need to pay for.
#12 Transforming your venue from day-to-night
One word: lighting! Depending on how much is required, there might be an additional charge - alternatively, if your venue is unable to help you, you might need to turn to a prop-hire service to find what you need.
#13 Over-time costs
If timings over-run, your venue could charge extra. Check what their policy for extensions are and remember that staying later than stated will most likely be expensive as staff will need to be paid more.
#14 Getting your dress dry-cleaned
You might not consider this to be an essential but remember: it's going to be stored away for rather a long time, so you might as well hang it up in pristine condition.
#15 Applying for copies of your marriage certificate
If you need to update your driving license or passport, you'll need fresh copies of your marriage certificate.