Whtiening had different results from person to person depending on the structure of your teeth. No dentist will be able to tell you the result you will acheive. Did you get your home whitening kit from your dentist? If so then did you wear your whitening trays every day for 2 hours for 2 weeks? If this has not worked then i doubt any sort of teeth whitening will work for you. Did you take tetracycline as a child? If so then this stains your teeth while they are developing and would therefore be impossoble to get a perfect result with whitening.  
If you have not tried the home whitening trays from a dentist then this method is the least costly way to whiten you teeth (£395 at my Clinic). If you have already tried this but did not wear your trays for 2 hours for 7-14 consecutive days then i suggest that you buy some more whiteing gel from your dentist and try this method again (you trays will still be good to use and the whitening gel cost around £50 for a weeks worth).
If you have tried both of these above and/or have taken tetracycline as a child then then the next option is Veneers. Veneers are considerably more expensive than whitening (from £795 per tooth at my Clinic) and are a lot more invasive than teeth whitnening and need to be replaced every 10-15 years.

I’m sorry if this is not what you wanted ot hear but hopefully this information has been some help to you.

Kind regards
Dr Justin Glaister