Well Rhox is worth about £2 so your already up in terms of what you paid
Id keep them if your interested in the game. I played about 12 years ago but finally picked it up again a year or two back and whilst I play fairly competitive decks I don't want to put the money in required to really place at proper pro tour qualifiers, I have still managed placings at Friday Night Magic events [which usually have 30-50 players, its like a one night tournament every Friday] and won boosters from it.
Theres a group of us who play and although 2 of the guys put a lot of money into the game the rest of us just play casual and pickup a booster here and there, there are lots of different formats to suit however you want to play. Standard is hard to keep up with as it has to be current cards.
Me and a few of the group have started to play a friendly format called Commander [EDH] which is much cheaper to play, stops a lot of silly combos as you can only have 1 of each card and its just more fun really.
What I do like about Magic in general is that its so easy to pick up and play/pack away etc. Quite often when we are sat around after doing something else we will just have a few games as its so easy to get a game going. I think its well worth doing if its something your group would be into just as a little side game to pass the time now and again and if you all keep it casual and not put loads of money into it and go for killer decks it can stay very fun.
Duel Decks are often a fun way of getting into the game. Its sets they release with 2 decks in and each deck has a certain theme, ive had lots of fun just using the original decks from duel deck sets against a person using the other.
If your looking to start, the duel deck 'Phyrexia vs the Coalition' is probably the cheapest [can get it for as low as £8 new usually] and I really enjoyed the completely different playstyles in the decks.