OK so I admit I didn't read all the other replies thoroughly so sorry if I repeat anything or follow the wrong lead. I'm replying to the original posting.
As you appear to be either in the UK or at least able to use a UK bank (Barclay's), and as I'm a UK expat living in the Dominican Republic (DR), here's what I do:
I send all my money to the DR, from the UK, using Currencies Direct (
Currency Exchange | Foreign Exchange | Online Forex (FX) Dealers, telephone from the DR is 011 44 20 7847 9400). They offer two services (at least): the ability to send an amount monthly from a UK Bank to a DR bank account and the ability to send a one-off payment. In either case I've used Scotiabank and Banco Popular, though I believe all main DR banks will be able to be used.
The main benefits of using Currencies Direct are that the money is available as soon as it arrives in your bank, the exchange rate is very competitive (much better than any bank will give you) and the company charges nothing for the service (yes, it's free) if it's a regular monthly transfer (there's probably a minimum amount) or, for one-off payments, if the amount is 5000 pounds sterling or more.
If doing this, you should transfer pounds but to arrive as US dollars and you will need a receiving US Dollar account. Check your DR bank's policy on dollar accounts (e.g. Banco Popular charges a fee if your account is below 500 US Dollars at the end of a month but otherwise is free).
If you send a large sum, you will need proof of origin so as to show the money is not being laundered. Proof means not just where it came from but how the money was obtained (e.g. from sale of a house, lottery win, etc.). Each bank has its own policy on this and Scotiabank leaves the policy up to each individual branch manager!!! So check with your bank before sending anything so that they do not lock it in on arrival!
Again, if using Currencies Direct, the fastest method is to phone them to agree the deal and then instruct your bank to arrange payment directly to Currencies Direct's HSBC bank in he UK. This is normally an instant payment if you bank with HSBC or may take up to 2 days otherwise. Your money is sent as son as the receive payment and you get email confirmations of the deal, payment receipt and payment despatch. Money usually takes 2 - 7 working days to arrive, usually nearer to 2-3 days but this is NOT within the control of Currencies Direct and is instead cause by the whims and fancies of the secretive banking world's processes (your money passes through the USA and who knows what they do there?)!!! As long as you provide correct details to currencies Direct and don't break any D laws, your money is guaranteed to arrive. If you prefer to pay by some other means, they accept several methods of being paid - ask them.
Once your money has arrived, if you are definitely paying in US Dollars, there's no need to do anything else. However, if you are meant to pay in US Dollars (or the seller quotes a US Dollar price only), ask what the DR Pesos price is. Then if checking if a Pesos purchase is better than a dollar purchase or if paying in Pesos anyway, check out the rates to change your dollars. All official DR banks (Popular, Scotiabank, Reserva, etc.) will give you an official rate that is significantly WORSE than a black market bank. So check black market bank rates. However, if you feel the need to use a black market bank, you must NOT use one for any significant amount unless you travel accompanied by someone (ideally several people) who you trust (fully) and who are armed with legal pistols or shotguns, preferably the latter. For amounts large enough to buy a finca, you will profit by many thousands (probably tens of thousands) of Pesos if you do this but please do assess the risk. Incidentally, it's not a good idea for a foreigner to use a DR Black Market bank as any "tigere" watching the bank will identify a foreigner instantly and suspect they will leave the bank with enough pesos to make a robbery interesting. However, if a Doinicano enters a Black Market bank, "tigeres" tend to think they will be changing just $5 or $10 making a robbery too high risk for the likely low profit. Of course, to benefit from this, you need to trust a Dominicano!!!
In any event, I assume you know not to pay for the finca in cash mainly as it requires that you walk around like a target waiting to be hit!!!
Well, that's enough from me. If you need to know more abut this, just ask direct questions and I'll hope to spot the reply. Alternatively, send me a private message.
If you end up using Currencies Direct, please do say you were referred to them by me (please ask in a private message for my details) and check if they'll pay me a commission without you and I having to fill out forms!!! However, I'm not telling you all this for the commission as I truly use them myself for all my money transfers to the DR, so I do recommend them.
As to using XE, their rate is probably slightly better as they guarantee that they offer the best rate available anywhere (or it it just for internet service providers?). However, I've never tried them so can't really offer anything helpful on that subject.
Cheers