i think it is right that delphion is not for free, but in "http://patents.uspto.gov/" you can search for us patents and get good results. another search engine is "http://ep.espacenet.com/" for european patents (i'm not sure but i think here you will get world wide patents).
try this two pages. in the beginning it is a little bit tricky, but in the end there are useful results.
Hi,
I search in delphion pat by key word and look first page ..then i use pat number in pat number search in "http://patents.uspto.gov/" and by "Alternatiff" plugin read pat. Then i save the tiff images and convert it in pdf
by Acrobat
Best,