Listing here does not imply either endorsement nor that it has been inspected for quality. All prices cited are for ONE night and were given as of mid-September 2014 - many will go up steeply if you wait and may vary - they are provided for guidance

For those who wish to browse for accommodation - try these websites:

 

http://www.booking.com/

http://www.travelsupermarket.com/c/hotels/england/london/

http://www.accommodationlondon.net/

http://www.travelstay.com/

http://uk.hotels.com

http://www.budgetplaces.com/

 

If you want to risk late booking but also want to see if you can get substantial discounts, try:

http://www.laterooms.com

http://latebooking.com/

http://www.lastminute.com

 

For cheap youth accommodation (youth hostels) try:

http://www.yha.org.uk/

 

Listings

Clink78
backpacker hostel with dorms but also some twin rooms. Prices seem to vary with occupancy - average for Dorms is £25-30 and rooms upward from £60
http://www.clinkhostels.com/london/backpacker-hostels/clink78
The Generator Hostel
Compton Place - London WC1H 9SD - Listing £30 dorm beds and relatively cheap £35+ basic rooms but minimum 2 nights booking)
www.generatorhostels.com
The Indian YMCA
YMCA Indian Student Hostel, 41 Fitzroy Square, London, W1T 6AQ ( You do not need to be young, a student, or Indian to stay there) - Listing £25+ for dorms and circa £60 for rooms. Prices include both breakfast and dinner. 
http://www.indianymca.org/
European Hotel
11-15 Argyle Square - Kings Cross WC1 - Listing from £45 basic single to £80 en-suite double
www.travelstay.com:80/pages/EuropeanHotel.htm?affcode=RA
Garth Hotel
69 Gower Street - London WC1E 6HJ - Listing £60 single upwards
http://www.garthhotel-london.com
Imperial Hotels Group
offering a range of deals focused around the Euston/Bloomsbury Area
County Hotel
Upper Woburn Place, London WC1H 0JW - Listing £52 - 60 (but not en-suite)
Tavistock Hotel
Tavistock Square, London WC1H 9EU - Listing £81-107
President Hotel
Russell Square, London WC1N 1DB - Listing £86-115
Royal National Hotel
Bedford Way, London WC1H 0DG - Listing £86-£111
Bedford Hotel
Southampton Row, London WC1B 4HD - Listing £93-124 (and a little farther away)
Imperial Hotel
Russell Square, London WC1B 5BB - Listing £95-£126 http://www.imperialhotels.co.uk/
Crescent Hotel
49-50 Cartwright Gardens London WC1H - Single Listings from £61 basic to £100 en-suite
www.crescenthoteloflondon.com
The George Hotel
58-60 Cartwright Gardens, London WC1 9EL - Listing around £60 for single basic, £90 single en-suite and doubles starting from £90

www.georgehotel.com

Central Hotel
16-18 Argyle St London, England, WC1H 8EG - Listing from £85 for a double room
Book via www.hotels.com
The Fairway Hotel
13/15 Argyle Street, King's Cross, London, England, WC1H 8EJ - Listing at £91 - £104 for a double room <> Book via www.hotels.com

NOTE - Argyle Street London WC1H 8EJ to R has a large number of small hotels with rooms all around the £90-£110 price range - they are best accessed and booked through the website below http://www.budgetplaces.com/5564/king-s-cross-station-accommodation-london-sort-by-distance-701-9.html

Arran House Hotel
London WC1 - listing from £95 single without ensuite to £155 single en-suite and upwards
http://www.arranhotel-london.com
Crestfield Hotel
3-4 Crestfield Street London, England, WC1H 8AT - Listing £95 for a double room
www.hotels.com
Alhambra Hotel
17-19 Argyle Street London, England, WC1H 8EJ - Listing £108 for a double room
Book via www.hotels.com

 

Jesmond Dene
27 Argyle Street, Kings Cross St Pancras, London, England, WC1H 8EP - Listing £108-£120 for a double/twin
Book via www.hotels.com
King Cross Inn Hotel
9-11 Euston Road London,England
NW1 2SA - Listing from £113 for non-cancellation Singles and Doubles
Book via www.hotels.com
Arriva Hotel
55 Swinton Street, Camden, London, WC1X 9NT - Listing from £111 for a single room and £120 for a double
Book Via www.booking.com
Comfort Inn - Kings Cross/St Pancras
31-33 Argyle Street, Camden, London, WC1H 8EP - Listing from £115
Premier Inns
-
rather anonymous accommodations but normally comfortable

26-30 York Way, Kings Cross - Listing at £122-160

88 Euston Road, London - Listing at £120-50

http://www.premierinn.com/

The California
4-8 Belgrove Street London, England, WC1H 8AB - Listing £129 for a twin or double
Travelodges - rather anonymous accommodations but normally comfortable
100 Kings Cross road - Royal Scot - Listing prices at £140

http://www.travelodge.co.uk/hotels/269/London-Central-Kings-Cross-Royal-Scot-hotel

356-364 Grays Inn Road - Central London Kings Cross - Listing prices at £145

http://www.travelodge.co.uk/hotels/258/London-Central-Kings-Cross-hotel

10 - 42 Kings Cross Road - London Farringdon central - Kings Cross area - Listing prices at £136

http://www.travelodge.co.uk/hotels/270/London-Central-Farringdon-hotel

1-11 Grafton Place - Euston area (a little farther away - Listing prices at £142

http://www.travelodge.co.uk/hotels/344/London-Central-Euston-hotel

Holiday Inn Bloomsbury

Listing prices from £175 per night - strictly for Comrades with bourgeois deviationist tendencies

http://www.ihg.com/holidayinn/hotels/gb/en/london/lonkc/hoteldetail