There is alot of options for a tank this size, but depends really on what you like, also as the width is only 18inch it limits some types of fish, however still a large community would look amazing in there..
2 Parrot fish
12 Inch Plec
14 lovely clown loach 4 inch to 7 inch
4 8 inch Tinfoil barbs
4 5 inch kissing Gourami
Then you could trawl the classifieds all around, also advertise to rehome unwanted fish on places like gumtree and aqauriast classifieds...
Or when you get money then keep treating yourself,dont have to go mad...
personally for me i do not like parrot fish so id rehome them..lol
I have a couple of rainbow cichlids which look good and are peaceful..also chocolate cichlid,ive had it about 3 years i think and as of yet it has not picked on anything what so ever and they are stunning to look at
the tinfoils sound a nice size,and they will double in size so remember that,i had to rehome mine as they outgrew my 5/2/2ft.. as with the plec they can obtain some size,depending on plec,i had a gibbicep plec and it recently died,when i took it out of tank i had to measure and it was 20inch from nose to tip of tail..was large..
if you going community id reccomend you looking at something like Puntius filamentosus if you can find them, they look great when matured..
also spanner barbs/Puntius laterstriga