Hello,
Being your first time i understand why you think you don't wanna go alone. I went first time in 2004, with friends, didnt know what to expect...
As of today i have been to Negril,Jamaica 16times. Many of them alone. Negril is a beautiful area of Jamaica. It's very safe, not like Kingston or MontegoBay. Negril is still very much in it's natural state. I can strongly suggest to you in regards to safety you wont have a problem Mon! In terms of cost you have 2 choices. To pick an All inclusive package (plane, transportation, hotel, food and drinks) or you can book your own plane, your own transportation and chose a smaller resort much less expensive. I have a website with more Negril information.
Feel free to browse and get familiar with Negril
Hope i was helpful
www.travel2negril.com