3D has come up with some great ideas. Afternoon tea voucher could be another or engraved mirror compact.
I could certainly make some suggestions for jewellery within your budget. My website is www.louloubelle.co.uk - jewellery is great for a present as it can double up to wear on the day and a present.
I have lots of bracelets on this page http://www.louloubelle.co.uk/bracelets_bridal.html which come in well under budget. If they were made with Swarovski pearls and siler plated they could also be personalised with silver plated initial charm (personalisation details can be found here http://www.louloubelle.co.uk/make_it_personal.html)




Or could you could get a pendant and earring set in silver plated:
Bardot is made with Swarovski crystals comes in at £16 for the set

Crystal Drop or Pearl Drop would be £20 for the set


All items comes gift boxed too so are all ready to give as presents.
I hope that gives you some ideas but if there isn't something perfect for you I could certainly make you something bespoke. Please drop me an email on lisa@louloubelle.co.uk if you'd like to go through anything.
Lisa
Lou Lou Belle Designs - handcrafted jewellery and hair accessories
www.louloubelle.co.uk lisa@louloubelle.co.uk Facebook