I'm getting a taxi from Ballinskelligs (Skellig Michael Islands) to Cahersiveen (on a Wednesday) because I read that's the closest bus stop. I won't arrive in Cahersiveen until about 4:30-5:30PM....I'm trying to get to Glendalough somehow but all of the bus routes seem to only leave in the morning, at the latest 12pm or 1pm. I'm open to taking the train but ran into the same problem of not being able to get there. I looked up how much a taxi might cost me from Cahersiveen to Killarney (for a possible bus/train transfer) and it's estimated at least 110 euros....way out of my budget. Can anyone help me? I'd be extremely appreciative of any advice....THANK YOU!!!

I venture to suggest that the lack of other replies suggests that, like me, many readers were scratching their heads at your apparent inflexibility when faced with a couple of obstacles.
Firstly, the only direct bus to Glendalough is the privately operated St. Kevin's Bus (www.glendaloughbus.ie) so you obviously need to go to Dublin and onwards from there.
Now to the real points that, as I say, people are probably a little perplexed by. So you've decided you'll have to get a taxi to Cahersiveen but will miss the bus. Obviously you have to restructure your day and take an earlier bus; you're the one that has to fit the bus schedule if you're reliant on it. Cahersiveen is about as far from Dublin as you can get, therefore it makes sense that buses will leave there in time to get to Dublin by evening.
It is entirely possible that you won't be able to take a bus from Dublin to Glendalough on that day - the last one goes at 1800. Reading between the lines, I suspect that, like many tourists, you've set your heart on doing every beauty spot that you can but sometimes you have to compromise. So I think a night in Dublin beckons followed by Glendalough the following day.
One possible alternative would be to see if you can get to Kerry Airport for the 1600 Ryanair flight to Dublin that arrives at 1650; you'd definitely have time to get to the evening bus then.
Thank you for the reply, Barryhennessy! I suppose I am inexperienced with Ireland's public transportation systems (especially considering I'm inexperienced using them here in the US, haha). I've drastically revised my trip, many destinations have gotten the chop, but I think it's better to have time to enjoy what I can realistically experience. It seems the most logical route for me to take to Glendalough, since I'll be coming from Ballinskelligs, is to take the train from Tralee to Dublin, then the next morning from Dublin to Glendalough to spend the day exploring by bicycle. I wish I had the money (or confidence!) to rent a car, but I don't. Thank you very much again for your help!
Cycling to Glendalough will involve some hills, possibly rain and wind so you will need to be prepared. Also the beginning of the journey, getting out of the city, will involve some busy roads. Not clear whether you intend staying down in Glendalough area for a couple of days but I don't think it would be very practical to try and cycle it as a day trip.
As BarryH has said, it is simply not possible to get to Glendalough easily from Caherciveen in a day. Both are pretty remote, and at far ends of the country.
In terms of getting to Glendalough, there is a train to Rathdrum, which is about 13 km south of Glendalough. Its possible to take a bike on that train, so if you want to visit by bike, the best way may be to take the train there, and cycle back to Dublin. The road directly north from Glendalough to Dublin on the R115 is a spectacular cycle, although quite tough as there is a big climb up to the Sally Gap. Its about 50 km from Glendalough to Dublin on that route. Its also possible to take a bike on the Dart (Dublin regional commuter train) at off peak times to Bray or Greystones, leaving a fairly modest cycle to Glendalough (although there is still a tough climb).
But cycling in that area is fantastic, if you can get a bike, and you think you can handle the hills, do it.

Just wondering about exploring by bicycle. As PhilipD has mentioned, the trip from Dublin to Glendalough by bike is fun but tough - it's about 70km with some very steep climbs, very exposed to the elements and quite isolated. If you have a good bike, decent clothing in case of bad weather (quite possible I'm afraid the way things are looking at the moment) and can at least fix a puncture - given that you could be 15km from the nearest village in some places - it's quite do-able. But if you're relying on hiring a bike, I'm not sure if you'll be able to get one that could be pleasurably cycled up the mountain roads. Generally the quality of hire bikes in Ireland is pretty poor, as far as I have seen.

Of course, as occurred to me afterwards, there is a feasible cycling route from Dublin to Glendalough that avoids most of the hills and sticks in inhabited areas, if you leave Dublin via Sandyford and head through Enniskerry and Roundwood. It's still long but a lot easier. Of course, it's less scenic, and less fun if you're a mad cyclist. If you do want to cycle to or from Glendalough and you end up with a not great bike, it's an option. PhilipD's idea of getting the train to Rathdrum is maybe the best option.