Do you mean that you would try to get a ticket in the section of the Barca-supporters (+- 99.000 seats), rather than in the section for the away-supporters (+- 1000 seats)? Someone correct me if I'm wrong, but I think I once read that for CL-fixtures, in case you have the same nationality as the visiting team (Scottish in this case), you're not allowed to buy a seat in the section of the Barca-supporters.
Which price-range are you looking for? In case you want about 50 euro per night, you could stay at the following hostel: "Hostel Conde Guell". I haven't stayed there, but it's recommended by some guys on the forum here, and quite close to Camp Nou. No private bathroom though.
I've stayed in Hotel Abba garden before (+- 15min away by foot from Camp Nou, about 100 euro per night). The hotel you friend stayed in was Princesa Sofia, that's quite expensive indeed. I think the visiting team sometimes stay there though (or else in the Hotel de rey juan carlos), so you might run into some Celtic players
If you plan to stay some days in Barcelona though, then I wouldn't recommend to stay in a hotel close to Camp Nou. Better to stay closer to the center of the city, there's way more to do there, and the Camp Nou is still easily reachible by metro (take the green L3 line to "Les corts")
Have fun in Barcelona, it's a magnificent city, can't wait to go back already